91 Explorer no temp or fuel gauge

[icytower387]

so i just bought my very first vehicle, and it's a 91 explorer right, but neither the temp nor the fuel gauge work, when you turn the key however, the needles on the gauges do move a liiiiittle bit down, but not alot
everything else electrical works fine

suggestions?

 

[icytower387]

ok
so from what i've gathered it could be the fuel sending unit or it could be something in the dash right? so i go to try to take the dash apart to take the cluster out and i unbolt the P R N D indicator and when i try to pull the cluster out to remove the plugs and cables, it just won't come out like there's not enough slack at all for me to reach in there, it barely moves at all, like less than an inch
this truck does have a 3" body lift so maybe the cables just don't have enough slack or whatever.
what do i do now?
can someone answer me?

 

[BKennedy]

With that body lift, you might not have enough slack in the speedometer cable and have to remove the other end from the transfer case.

 

[icytower387]

thank you for replying and yes, i did remove the speedo cable from the transfer case using this guide How to: Remove 1991-1994 Dash with lots of pics
but i can't seem to feed it past the firewall? something is stopping me, i released the cable from a clip that was riveted to the body, but there's something further up that's not letting me push the cable in

--Edit--
yeah so i unplugged the speedo cable from the transfer case and i did get alot more slack and was able to pull the cluster out further BUT, still not far enough to reach in and unplug the speedo cable. how do i release the cable even more? as if i were to replace it for example

--Edit 2-- so i cannot find any information on how to replace a speedo cable for this truck, and to be specific the speedo cable housing

it's been 3 days, i just want this fkin gas gauge to work damn it, im trying to check if it's the slosh module but i... CAN'T

 

[icytower387]

update: i managed to get the cluster out, (without anyones help) and since im so nice im going to post what i did:
so, if you're stuck like me you're at the step where you disconnected the speedo cable and still nothing
make sure the cable isn't clipped to the body anywhere (mine was) and unclip it
then you gotta unscrew the panel where the hood release is (the screws are at the bottom)
then you have to lower the steering column, which is just two big black bolts facing upwards (you can refer to the 22nd image on this post How to: Remove 1991-1994 Dash with lots of pics)
my truck is a little rusty so i had to pull the column down a bit, it doesn't drop to the floor but it comes down quite a bit.
after that, it was (somehow?) easier to pull on the dash and i had like way way more slack, i was able to access the speedo cable plug on the back of the cluster, and yeah, what you do is push firmly on the flat piece and this will shift the whole white plastic lock thing just enough to allow the cable to release as you pull at the same time
the other two plastic plugs are pretty self explanatory

 

[RangerX]

So does it work now?

 

[Roadrunner777]

I'm sorry you got this far, and so frustrated. Your first post was Saturday night, and it's fall... people are doing stuff. LOL, you're so frustrated I almost hate to post this!

The temperature gauge and fuel gauge only have one thing in common, the 12V supply voltage. So, if any other gauge DOES work, then it's possible, but unlikely your issue is in the gauge cluster, because other gauges using the same 12V source work fine, I gather.

I think you just might have a bad fuel sender and a bad temp gauge. I'm going to address these separately:

Fuel Gauge - The fuel gauge reads a sending unit in the tank. The sender is a simple variable resistor, with one end grounded. The resistance spec is 22.4 Ohms empty, 145 Ohms full. So, you can use the ohm function of a common digital test meter to verify the sender. The wire from the sender to the gauge is yellow with a white stripe. You can get to it at two places. The first is near the tank, the pigtail from the fuel pump. The second place is a circular connector with 8 positions under the hood, just under the master cylinder.

For the pigtail at the tank, disconnect the connector and figure out which end goes to the tank. Then use your meter to measure resistance from the white/yellow wire to ground, which is the black/yellow wire. Do this with the ignition off. It should give you somewhere between 22 and 145 ohms, like I mentioned before. If you do this right, and get a solid measurement outside that range, that is the definitive test for the sender and you will have to replace the pump/sender unit. Doing the resistance test at the tank takes about 15 minutes if you have and understand a voltmeter and resistance measurement.

If your resistance is in range and makes sense compared to how full you think the tank is, then go on to the connector under the hood and do the same thing, except that you won't have a ground in that connector, you will have to find some bare metal for the ground. The wire to measure is, again, yellow/white, and again, engine off, please. If memory serves, you want to measure the male side of the connector, but don't count on my memory. If you don't get a value on one side of the connector, test the other side! You should get a value similar to the measurement at the tank. If not, then you have a wiring issue from the tank to the engine bay. If that's the case, we can get into how that harness is routed.

Temperature Gauge - This is somewhat similar. 74 Ohms cold, about 10 Ohms hot. The sender for that is near the thermostat housing, the sender has a single pin connection. Now, just for future reference, there are actually two temp senders, one for the gauge, the other for the engine computer. The engine computer sender has two wires and a plastic connector. Measure resistance from the sender pin to ground for the sender at the thermostat and see if that makes sense in the range I mentioned.

Both of these senders have a significant history of failure. You can do all of these tests in 30 minutes or less. I would rule out the senders before going any further with the gauge cluster. But, since you apparently have the gauge cluster out now... you might consider two unrelated things. First, I highly recommend you replace all the illumination lights in the cluster. This is cheap, easy and you will be staring right at them, so why not. I mean, they are 25 year old light bulbs.

Second... if you are not aware of the oil pressure gauge/switch issue, the oil pressure gauge is not an actual gauge. It uses an oil pressure switch and if there is oil pressure, it moves the gauge needle to a certain position. You can make this work like an actual gauge though. To do it, you need replace the sender switch with a common analog oil pressure sender. That's easy, you get to it from underneath, it's towards the front drivers side. But you also have to do a modification at the gauge cluster, you have to bypass a 20 ohm resistor. Here's a thread on the oil gauge: How to: Make Oil pressure gauge perform like "real" gauge

If the sensors are ok, then we can talk about the wiring in the gauge cluster itself. I have helped about a dozen people with the fuel gauge. Only one of them ended up with a problem at the gauge cluster.

Finally, there is a factory manual with wiring diagrams and test procedures for the various switches and systems. This is the EVTM manual and they are all over Ebay for less than $20. Get one of these... you will not regret it.

I try to check this forum daily, usually early morning. But, this being fall, and me being in northern MN, I am busy getting ready for winter, including a pretty major repair job on another truck. But, ask your questions and I will do my best to help.

 

[MrQ]

update: i managed to get the cluster out, (without anyones help) and since im so nice im going to post what i did:
so, if you're stuck like me you're at the step where you disconnected the speedo cable and still nothing
make sure the cable isn't clipped to the body anywhere (mine was) and unclip it
then you gotta unscrew the panel where the hood release is (the screws are at the bottom)
then you have to lower the steering column, which is just two big black bolts facing upwards (you can refer to the 22nd image on this post How to: Remove 1991-1994 Dash with lots of pics)
my truck is a little rusty so i had to pull the column down a bit, it doesn't drop to the floor but it comes down quite a bit.
after that, it was (somehow?) easier to pull on the dash and i had like way way more slack, i was able to access the speedo cable plug on the back of the cluster, and yeah, what you do is push firmly on the flat piece and this will shift the whole white plastic lock thing just enough to allow the cable to release as you pull at the same time
the other two plastic plugs are pretty self explanatory

We do the best we can around here, but first gens are not quite as well known as second gens and not as many people know its quirks, thus this forum see's less traffic. But, it seems you found a way around your issue which is great.

I'm sorry if you feel we were unhelpful, but you need to understand we don't do this for a living, but rather as a hobby. We have no set hours to spend on the forum or a quota of helpful responses to meet and not all of us have the same level of knowledge on these issues as others.

However, this whole forum has millions of posts about issues and more than likely your question has been asked and answered before. This where the search function comes in real handy to mine that treasure trove of knowledge for a more immediate response to your question. And now your solution will be added to that knowledge.

 

[BKennedy]

MrQ said it. I was going to respond in kind, but he beat me to it. I'm sorry that when I said you might need to disconnect the transfer case end of the speedometer cable I failed to mention that there is also a clip about mid point on the underside of the body. The only reason I know that is because I have been under my Explorer swapping out a transfer case for the last month and have seen it several times. I failed to mention it because it sounded like you knew what you were doing and didn't need the entire process spoon fed to you.

A simple search revealed numerous threads on this forum
https://www.explorerforum.com/forums/index.php?threadloom/search

Also, you really don't need to remove those steering column bolts to take the dash face off. It pulls off once you remove the bolts holding the ask tray frame in place and unplug the wiring to the headlamp and cargo hatch controls. You can push down on the hazard light switch and pull it straight off. Before you reinstall the dash face, I suggest you strengthen all of the push plug mounts with some 5 minute epoxy. They were not meant to last this long and break with repeated removal and replacement. I have probably been into my dash more than anyone on this forum since I had to completely replace it when I had an electrical fire and it melted. There is not much slack on the instrument cluster wiring harness or the speedometer cable and its a pain to remove and replace. The trick is to be very slow and careful without forcing anything.

 

[icytower387]

I'm sorry you got this far, and so frustrated. Your first post was Saturday night, and it's fall... people are doing stuff. LOL, you're so frustrated I almost hate to post this!

The temperature gauge and fuel gauge only have one thing in common, the 12V supply voltage. So, if any other gauge DOES work, then it's possible, but unlikely your issue is in the gauge cluster, because other gauges using the same 12V source work fine, I gather.

I think you just might have a bad fuel sender and a bad temp gauge. I'm going to address these separately:

Fuel Gauge - The fuel gauge reads a sending unit in the tank. The sender is a simple variable resistor, with one end grounded. The resistance spec is 22.4 Ohms empty, 145 Ohms full. So, you can use the ohm function of a common digital test meter to verify the sender. The wire from the sender to the gauge is yellow with a white stripe. You can get to it at two places. The first is near the tank, the pigtail from the fuel pump. The second place is a circular connector with 8 positions under the hood, just under the master cylinder.

For the pigtail at the tank, disconnect the connector and figure out which end goes to the tank. Then use your meter to measure resistance from the white/yellow wire to ground, which is the black/yellow wire. Do this with the ignition off. It should give you somewhere between 22 and 145 ohms, like I mentioned before. If you do this right, and get a solid measurement outside that range, that is the definitive test for the sender and you will have to replace the pump/sender unit. Doing the resistance test at the tank takes about 15 minutes if you have and understand a voltmeter and resistance measurement.

If your resistance is in range and makes sense compared to how full you think the tank is, then go on to the connector under the hood and do the same thing, except that you won't have a ground in that connector, you will have to find some bare metal for the ground. The wire to measure is, again, yellow/white, and again, engine off, please. If memory serves, you want to measure the male side of the connector, but don't count on my memory. If you don't get a value on one side of the connector, test the other side! You should get a value similar to the measurement at the tank. If not, then you have a wiring issue from the tank to the engine bay. If that's the case, we can get into how that harness is routed.

Temperature Gauge - This is somewhat similar. 74 Ohms cold, about 10 Ohms hot. The sender for that is near the thermostat housing, the sender has a single pin connection. Now, just for future reference, there are actually two temp senders, one for the gauge, the other for the engine computer. The engine computer sender has two wires and a plastic connector. Measure resistance from the sender pin to ground for the sender at the thermostat and see if that makes sense in the range I mentioned.

Both of these senders have a significant history of failure. You can do all of these tests in 30 minutes or less. I would rule out the senders before going any further with the gauge cluster. But, since you apparently have the gauge cluster out now... you might consider two unrelated things. First, I highly recommend you replace all the illumination lights in the cluster. This is cheap, easy and you will be staring right at them, so why not. I mean, they are 25 year old light bulbs.

Second... if you are not aware of the oil pressure gauge/switch issue, the oil pressure gauge is not an actual gauge. It uses an oil pressure switch and if there is oil pressure, it moves the gauge needle to a certain position. You can make this work like an actual gauge though. To do it, you need replace the sender switch with a common analog oil pressure sender. That's easy, you get to it from underneath, it's towards the front drivers side. But you also have to do a modification at the gauge cluster, you have to bypass a 20 ohm resistor. Here's a thread on the oil gauge: How to: Make Oil pressure gauge perform like "real" gauge

If the sensors are ok, then we can talk about the wiring in the gauge cluster itself. I have helped about a dozen people with the fuel gauge. Only one of them ended up with a problem at the gauge cluster.

Finally, there is a factory manual with wiring diagrams and test procedures for the various switches and systems. This is the EVTM manual and they are all over Ebay for less than $20. Get one of these... you will not regret it.

I try to check this forum daily, usually early morning. But, this being fall, and me being in northern MN, I am busy getting ready for winter, including a pretty major repair job on another truck. But, ask your questions and I will do my best to help.

yee i figured that people must be out working or doing other things, it's whatever, and yeah i came to the conclusion that it's most likely the fuel sending unit after doing some more digging and bypassing the slosh module (which yielded the same result as before).
and now i'm going to use all of your instructions and will post back to see what i find!
Thank Youuuu

 

[icytower387]

MrQ said it. I was going to respond in kind, but he beat me to it. I'm sorry that when I said you might need to disconnect the transfer case end of the speedometer cable I failed to mention that there is also a clip about mid point on the underside of the body. The only reason I know that is because I have been under my Explorer swapping out a transfer case for the last month and have seen it several times. I failed to mention it because it sounded like you knew what you were doing and didn't need the entire process spoon fed to you.

A simple search revealed numerous threads on this forum
https://www.explorerforum.com/forums/index.php?threadloom/search

Also, you really don't need to remove those steering column bolts to take the dash face off. It pulls off once you remove the bolts holding the ask tray frame in place and unplug the wiring to the headlamp and cargo hatch controls. You can push down on the hazard light switch and pull it straight off. Before you reinstall the dash face, I suggest you strengthen all of the push plug mounts with some 5 minute epoxy. They were not meant to last this long and break with repeated removal and replacement. I have probably been into my dash more than anyone on this forum since I had to completely replace it when I had an electrical fire and it melted. There is not much slack on the instrument cluster wiring harness or the speedometer cable and its a pain to remove and replace. The trick is to be very slow and careful without forcing anything.

also on the push plug mounts...

ahhh~ i'll figure those out after im done with these gauges

*edit* also i realize in my other post it's unclear where i say
"the panel where the hood release is" (im just going to edit that and use pictures tbh)
but this is what i meant:

(im holding it because the steering column is lowered atm)

 

[icytower387]

so, since i needed a floor jack and some jack stands to change my tires (rear ones are bald, and i bought 4 tires from the same guy i bought the truck from for 400 cad$, 31's)
and the guy that was going to get a friend of his to borrow him the jack and the stands asked me:
"Hey uh, how about we check the alternator, just to see, you know?"
so i did
i used some guide from the internet, but what it said was to do the following:
"place your multimeter probes on the battery terminals when the truck is running and you should see 13.5 to 14.5 volts"
i was seeing 12.5 and was like "uh, ok"
then it said:
"turn on lights,heaters,defrosters, etc to load the alternator and then check the voltage again, it should lower a bit and then stabilize at 13.5 to 14.5"
it went from 12.5 to 12.1 and i was like "well F"
so then it said:
"but it could still be a fusible link between the battery + and the alternator, located after the starter relay"
and i confirmed this by opening a haynes manual that i bought and sure enough

there was the fusible link, but i couldn't find it physically, and the guy and i came to the conclusion that the previous owner just spliced it together, but im not sure as im writing this, so, if you could, send some pictures of what this fusible link looks like inside the engine bay and stuff? and where to find it? i took my battery out to get better access and still couldn't
so idk.

 

[Roadrunner777]

On the starter relay, you will find one post with about three wires. One of those goes to the battery, another to the alternator. Trace the wire from that post to the alternator, it should be in-line somewhere. That's less than 3 feet of wire, should be pretty obvious.

That said... the alternator has very little output at idle. Try it again and bump the throttle a little bit. If the voltage goes up, you're fine.

 

[BKennedy]

On the starter solenoid on the passenger side fender there should be a wire splitting into two wires, then back to one. The two wires are your fusible link. All of them I have seen are gray or white.

 

[icytower387]

uhhhh, im somewhat confused,
so i took pictures!

yeah so uh i unhooked everything, and idk where this thing is, where the electrical tape is though is where we tried to open it and see if there was something there?? but there wasn't so i just don't know

*edit*
Imgur
that's just an imgur video of me not figuring out where this thing is

 

[icytower387]

On the starter relay, you will find one post with about three wires. One of those goes to the battery, another to the alternator. Trace the wire from that post to the alternator, it should be in-line somewhere. That's less than 3 feet of wire, should be pretty obvious.

That said... the alternator has very little output at idle. Try it again and bump the throttle a little bit. If the voltage goes up, you're fine.

i did what you told me to do and, the voltage didn't go up at all
im just changing the alternator at this point

 

[icytower387]

PLOT TWIST
i might be getting a parts car this sunday, thing is immaculate (well, i haven't seen it in person but from the pictures it looks like it) and yeah, good STUFF

 

[Roadrunner777]

Before you do that, check fuse #16 under the hood. It is used to energize the alternator, and if it blows, it will keep the alternator from charging, and oddly, the charge warning light on the dash will not go on to indicate this problem. Fuse #16 is one of the smaller ones in the middle group, should be 15A unless someone has changed it.

For what it's worth, on the fusible links, go to the alternator. Find the black wire with the orange stripe. Follow it away from the alternator... the links should be on that wire. Going away from the alternator, it will be black with orange stripe, then it will get to the fusible links. After the fusible links, it turns to two wires in parallel, both grey, both going to a post on the fender starter solenoid. So, as an alternative, you could find the two grey wires running together from the solenoid and trace those the other direction. Somewhere between the two are the fuse links. I don't know anything about appearance or exact location because I have a '94.

And, I should have disclosed this before. I'm giving you all kinds of ideas and wire colors. I am reading that for a '94 and assuming it is the same for your '91. So, do not take my postings as gospel-correct.

I will, though, tell you the alternator question has nothing to do with your original issues. It's a good thing to know your alternator is working, but a bad alternator will not cause two particular gauges to completely fail. They may read slightly lower with lower voltage available.

Also, as an aside for general consumption: The 90A (and really, the 130A too) alternator will not support everything turned on with the engine idling. Here's a chart of alternator output vs RPM:

I had the 90A alternator, and frequently had to run everything at once during winter snowstorms. At stoplights, everything slowed down... even the turn signal blinker. Now, it's not that unusual for people up here to spin out into ditches. Chains are illegal here, so it's all driving skills. So, in that case, stranded in a vehicle, at idle, the battery will eventually discharge if left idling with all the stuff on.

I went to a 130A alternator and it really didn't help. What fixed it was an overdrive pulley, a smaller diameter pulley for the alternator. This spins the alternator faster, relative to the engine and get's it up into a better charging range. This will, of course require a slightly shorter drive belt. I'm not really saying all this directly to this thread or issue. I'm just rambling on about alternators in general.

 

[MrQ]

That chart is really helpful @Roadrunner777 that should be in the electrical forum "Helpful Posts".

I upgraded to a 130a in my 1st gen and it made a difference, but I have also changed my headlights to LED's as well as my interior lights, so there is a lot less power draw. Boggles my mind why Ford ever went with a 95a on an Explorer, cheaping out I guess or they guessed that the bigger battery would help mitigate the limited charge at idle .

The EB's and Limiteds should at least have had 130's but my Limited came with a 95a.

 

[icytower387]

Before you do that, check fuse #16 under the hood. It is used to energize the alternator, and if it blows, it will keep the alternator from charging, and oddly, the charge warning light on the dash will not go on to indicate this problem. Fuse #16 is one of the smaller ones in the middle group, should be 15A unless someone has changed it.

For what it's worth, on the fusible links, go to the alternator. Find the black wire with the orange stripe. Follow it away from the alternator... the links should be on that wire. Going away from the alternator, it will be black with orange stripe, then it will get to the fusible links. After the fusible links, it turns to two wires in parallel, both grey, both going to a post on the fender starter solenoid. So, as an alternative, you could find the two grey wires running together from the solenoid and trace those the other direction. Somewhere between the two are the fuse links. I don't know anything about appearance or exact location because I have a '94.

And, I should have disclosed this before. I'm giving you all kinds of ideas and wire colors. I am reading that for a '94 and assuming it is the same for your '91. So, do not take my postings as gospel-correct.

I will, though, tell you the alternator question has nothing to do with your original issues. It's a good thing to know your alternator is working, but a bad alternator will not cause two particular gauges to completely fail. They may read slightly lower with lower voltage available.

Also, as an aside for general consumption: The 90A (and really, the 130A too) alternator will not support everything turned on with the engine idling. Here's a chart of alternator output vs RPM:

View attachment 174156

I had the 90A alternator, and frequently had to run everything at once during winter snowstorms. At stoplights, everything slowed down... even the turn signal blinker. Now, it's not that unusual for people up here to spin out into ditches. Chains are illegal here, so it's all driving skills. So, in that case, stranded in a vehicle, at idle, the battery will eventually discharge if left idling with all the stuff on.

I went to a 130A alternator and it really didn't help. What fixed it was an overdrive pulley, a smaller diameter pulley for the alternator. This spins the alternator faster, relative to the engine and get's it up into a better charging range. This will, of course require a slightly shorter drive belt. I'm not really saying all this directly to this thread or issue. I'm just rambling on about alternators in general.

i have my haynes manual here with the wiring diagrams and, the 1994 explorer diagram looks to be the same but with some extra stuff here and there, and it has 2 fuse links instead of one, but also, there is absolutely no fuse link anywere on this line from the alternator to the starter solenoid, you can see it in this video:
Imgur

also would you care to explain more about the pulley and alternator thing, i wouldn't want my truck to be starving for power in the middle of a snowstorm (i live in vancouver island) but more specifically, where to get this pulley and this...
slightly shorter drive belt..?