Ugh... 92 Explorer Hell..

[natenkiki2004]

In that case, I'm glad you took the right precautions regarding battery hookup.

Ok, key in vs key out in that case... does absolutely nothing. The only thing that happens when you insert the key is the chime circuit is closed and you'll get the chime sound when you open the door with the key in. That's it. It has no bearing on any other electrical system at all. It's only when you turn the key that circuits become activated.

It's good that everything looked fine, in a way. You need to test the relays. You saw the video on how to do that. You can also wait another day or two for my relays to arrive and simply swap them out to see if that makes a difference. In the mean time, you can do what you did today, take it all apart and hook up the battery again. This time, move the relays around. If they turn on/off, you definitely have wiring issues still, it may be broken contacts in the connector itself or still a physically & internally broken relay.


The only time you should start looking at the TPS and other sensors is when you can reliably pull codes/run the KOER test from the computer AND have no more of these phantom issues like the punch test or the dieseling. Then and only then can you start looking at other issues. Again, it means absolutely nothing to test sensors if the computer isn't behaving properly. It's like trying to switch around HDMI cables on your TV when the screen is broken. It'll make slight differences but ultimately it won't fix anything.

 

[MistahYebba]

So my PDB passes the punch test every time now after disassembling it yesterday and reseating everything. Why? Who knows... Loose relay?

So I re-read the codes today.. and KOEO is no longer 1-1-1! Yay something to diagnose!

Since I was getting 998 and 57 on KOER, I went ahead and got an octane bar from the junkyard. Code 57 is still there. Wasn't the octane thingy itself.

I also grabbed a TPS for good measure.

Same results with the junkyard TPS. Should've known it wasn't a sensor itself like you've been saying.

KOEO codes are as follows:

(KOEO): 539: System shows voltage at PCM pin 10 Is A/C on ? (What does this mean? The A/C was on during the test... am I supposed to shut it off to avoid this code?)

(CM):

122: TP sensor input is less than Self-Test minimum.
157: MAF sensor circuit open.
158: MAF sensor shorted to power.
211: PIP circuit failure.

I may have mixed up the 122 and 211 so I'm gonna re-read them to be 100% sure... but as you can see.... circuit, circuit, circuit, circuit..

I guess I need to get my hands on a multimeter.

 

[natenkiki2004]

My vote is still wiring, that area on the passenger side, anywhere from the ICM to the computer (inside the cabin). Very possible still that a relay isn't supplying enough voltage. You remember that EEC-IV Ford truck video from ScannerDanner?

 

[MistahYebba]

My vote is still wiring, that area on the passenger side, anywhere from the ICM to the computer (inside the cabin). Very possible still that a relay isn't supplying enough voltage. You remember that EEC-IV Ford truck video from ScannerDanner?

I sure do! That's why I picked up a multimeter today.

But let's say it is the ICM like that one guy said.

What about the ICM would be bad? It's so expensive to just guess-replace it. Even replacing the TPS was dumb even though it was $11. But at least I ruled out one more thing.

By the way, getting that KOEO about the AC was easy as turning it off before the KOEO test haha. 111s for that.

I also left out a code I'm getting.. it's 543.

Also -- I think I need those codes need a re-eval.. I think the descriptions are for KOEO.. but these are all continuous memory codes.

The real meanings would be...

122: Throttle Position Sensor Circuit Below Minimum Voltage
157: Mass Air Flows Sensor Circuit Below Minimum Voltage
158: Mass Air Flow Sensor Circuit Above Maximum Voltage
211: PIP circuit failure.
543: Fuel Pump Circuit Open–Battery To Powertrain Control Module (PCM)

Now I'm starting to feel like he was right and it is the ICM!

:/

 

[MistahYebba]

Tell me Natenkiki.. does this post (http://www.explorerforum.com/forums/showthread.php?t=365845) make sense to you??

He says "I disconnected the wire harness from the mass airflow sensor and checked voltage while runnning and was getting around 6 volts. So i figured it must be a bad mass airflow sensor, so I replaced that and it seems to have worked so far."

If he removed the wiring harness and tested it... and it's the wiring harness giving off 6volts, what the heck does that have to do with the sensor itself being bad?

The sensor isn't making the harness give off 6v... whatever gives voltage to the harness is making the harness give off 6v!

So... did he just get lucky? He has a very similar problem to mine.

 

[natenkiki2004]

I don't think it's the ICM because the ICM has nothing to do with TPS, MAF or fuel pump. The ICM is very very basic and basically does the math of counting the crank inputs to deliver spark timing to the computer. That's about it.

I don't know why a MAF would have 6v going back to the computer. Voltage out can't exceed voltage in and we all know that reference is 5v, usually a pinch less like 4.95v. The only way you'd get 6v is if the computer is seriously fried.

Let's just say for agrument though that the MAF is faulty, it still wouldn't explain the PIP, TPS or fuel pump codes.

The MAF is telling you that you're getting wild voltage swings. That's gotta be intermittent wiring OR a somewhat broken filament in the MAF. If you only had MAF codes, I'd bet that the MAF might be faulty everything still points to faulty wiring.

Go back to that C202 connector I showed you, take off the interior trim and look around, it's entirely possible that there's a problem in there.

 

[MistahYebba]

I guess what I'm mainly trying to understand so tomorrow when I start probing around I know what is going on..

How could you ever test the voltage of a SENSOR itself?

Testing the wiring harness isn't gonna test a faulty sensor? Cause that's the voltage that the harness is outputting.. not the sensor?

 

[natenkiki2004]

The only sensor that creates voltage is the O2 sensor and you're talking 1v. All the other sensors are resistance based, computer sends 5v, sensor reduces that based on activity and what's left is sent back to the computer. If you're testing the 5v reference, you're testing what the computer is sending to the sensor. If you're testing the return, you're testing what the sensor is doing. That's a way to see if your MAF, TPS, IAT, ECT, O2 and other sensors are bad.

 

[MistahYebba]

The only sensor that creates voltage is the O2 sensor and you're talking 1v. All the other sensors are resistance based, computer sends 5v, sensor reduces that based on activity and what's left is sent back to the computer. If you're testing the 5v reference, you're testing what the computer is sending to the sensor. If you're testing the return, you're testing what the sensor is doing. That's a way to see if your MAF, TPS, IAT, ECT, O2 and other sensors are bad.

There's no way that "6v MAF" guy in the post I sent you tested his return with the sensor unplugged..

 

[MistahYebba]

So all this time, you've been saying C202..

I research a bit more and see that C202 is my PCM.. I'm sure you knew that, and it even says it in the diagram you sent me, but I wasn't being very obeservant.. especially considering all of these terms are still new to me.

I'm gonna crack that bish open and see if I can find a blown capacitor!

Good tips, Natenkiki.... Good tips!

 

[natenkiki2004]

There's no way that "6v MAF" guy in the post I sent you tested his return with the sensor unplugged..

Correct.

So all this time, you've been saying C202..

I research a bit more and see that C202 is my PCM.. I'm sure you knew that, and it even says it in the diagram you sent me, but I wasn't being very obeservant.. especially considering all of these terms are still new to me.

I'm gonna crack that bish open and see if I can find a blown capacitor!

Good tips, Natenkiki.... Good tips!

Yep, C202 is the connector going to the PCM, all the goodies connect there. I doubt you'll see capacitor issues but if you do, they're probably not related. Capacitors hold voltage and are likely used to condition power to the computer and also hold/buffer power going out of the computer, like to the 5v reference. I mention C202 because it's a connector and has a lot of wires bundled and it's in a spot where it can get kicked & rubbed.

 

[MistahYebba]

Check this post out..just food for thought.

http://www.explorerforum.com/forums/showthread.php?t=189504

His problem turned out to be some capacitors I believe. Thought it was interesting and I was kind of inspired!

Kind of like early on in this post when I said my tachometer was way off.. and it only turned out to be a soldering issue!?

 

[natenkiki2004]

It is possible, I won't say it's not. I just feel like from your symptoms that it sounds more like a wiring issue. This was pretty sudden and with the fuel pump powering on when you hit the power distribution box, that's definitely wiring. Bad capacitors would cause erratic behavior only when you turn the computer on and it would be have better once the capacitors warmed up (turn the heat on or on a hot day with windows rolled up).

I work on computers and there's an old trick to tell if you have bad capacitors in your monitor. Often times a monitor will turn on then off over and over again. It's typically the capacitors in the high voltage circuit going bad. If you can heat them up enough (like with a hair dryer) they will work until they cool down.

 

[MistahYebba]

It is possible, I won't say it's not. I just feel like from your symptoms that it sounds more like a wiring issue. This was pretty sudden and with the fuel pump powering on when you hit the power distribution box, that's definitely wiring. Bad capacitors would cause erratic behavior only when you turn the computer on and it would be have better once the capacitors warmed up (turn the heat on or on a hot day with windows rolled up).

I work on computers and there's an old trick to tell if you have bad capacitors in your monitor. Often times a monitor will turn on then off over and over again. It's typically the capacitors in the high voltage circuit going bad. If you can heat them up enough (like with a hair dryer) they will work until they cool down.

My last monitor was slowly breaking and I knew it. It was always so bizarre. It would work all day and display crystal clear picture, but when I would shut it off to go to bed, getting it to turn back on in the morning was a pain. I would turn it on and off for about 5 minutes (no joke) until it finally would hold it's "on" state.

I knew it was capacitors, but when I went to take it apart to try and replace em, I tore one of the ribbon cables. It was a sad day. Haha.

I always wondered why it worked after turning it off/on... I guess they were heating up like you said?

------------------------------------------------------

As for my PCM... I took it out and opened it up. What do you know? Everything looked brand new on that circuit board!

Well... everything except the connector itself..

Check out these pictures and tell me what you think..

There's even a bug wing in there!

-----------------

So I wanna say, besides the corrosion (how can I clean it?)... the PCM itself should be ruled out.. I guess time to check out the harness like you said.. though I'm not sure what I'm looking for..

Is this harness where the TPS, MAF, and IAC get their power??

 

[natenkiki2004]

The computer will look clean because it should be sealed pretty well. That corrosion almost looks like water damage but I've not seen water damage first hand so I'm not 100% sure. Connector looks good, that crusty stuff on there is likely dielectric grease from the factory (the one spot they did put it on).

But yea, check the harness. That cable has inputs & outputs for the sensors, you'll see that in the wiring diagram I posted a couple pages back. You COULD even find the pinout and trace the actual wires, even do a few ohm tests or voltage drop tests but that's a bit excessive at this point.

 

[MistahYebba]

So help me out here.. I want to use this multimeter to check the voltages of each of the sensors and make sure they are all getting what they with the Key On Engine Off.

1. How do I know what they are supposed to be getting?
2. What mode does the multimeter have to be on to test properly?
3. Would I test the harness first by unplugging it from the sensor and making sure the harness itself is getting the correct voltage; then to further test, plug in the harness and backprobe it?
4. Let's pretend that all of the harnesses for my sensors are getting incorrect or too-low voltage... that means it's likely the "power supply" of these harnesses. That would be C202?

 

[natenkiki2004]

So help me out here.. I want to use this multimeter to check the voltages of each of the sensors and make sure they are all getting what they with the Key On Engine Off.

1. How do I know what they are supposed to be getting?
2. What mode does the multimeter have to be on to test properly?
3. Would I test the harness first by unplugging it from the sensor and making sure the harness itself is getting the correct voltage; then to further test, plug in the harness and backprobe it?
4. Let's pretend that all of the harnesses for my sensors are getting incorrect or too-low voltage... that means it's likely the "power supply" of these harnesses. That would be C202?

Have a look at this:
https://www.cdli.ca/courses/ep/predesign/t03/02knowledge-skills/images/activity13/multimeter1.jpg

You'll want to use the 20 VDC setting. Whatever you do, make sure you are NOT on ohms and that the probes are hooked up properly (NOT on Amps). As long as you're on VDC, you can't screw anything up.

1. All sensors work off of reference which is 5v.
2. Answered above.
3. Doesn't really matter. If you don't get 5v by backprobing, disconnect the sensor and try again.
4. If it's low voltage, it could very well be the computer. If it's 0 volts then it could be grounded out, then you need to look for a short.

 

[MistahYebba]

Read my MAF and TPS today since those are the only sensors I know of to read.

MAF gave me a 5.9V reading... a little high?

TPS gave me a steady 5V.

--

On the offchance that it matters, IAC gave me 12V and some other low voltage reading. Probably normal, seeing as it shouldn't have a 5V ref.

What do you think about the MAF harness reading?

I know ScannerDanner says high 5V usually means something with the ground.

What should my next steps be?

 

[MistahYebba]

Going to replace my fuel filter today just for kicks.. or at least give it a looksie!

I hear that can cause a hell of a lot of problems. Wouldn't be surprised if it's still the stock filter but the previous owner might have changed it.

**edit**

Also well aware that changing the fuel filter wouldn't do away with those CEL codes and the rest of my issues.. but it could give me a different playing field!

Especially because the inability to start the engine with the IAC plugged in started happening after sitting overnight the night I put cheapo fuel injector cleaner in.

Coulda knocked some crud loose and clogged up my fuel filter? Just a thought.

----------

Can't find anything online about the MAF sensor harness outputting 5.9v instead of 5v.

 

[natenkiki2004]

Fuel filter is a good maintenance item, especially if the history is unknown. I replaced mine when I got it, I knew the previous owner did it but I didn't know when or how many miles ago. Keeping records is nice.

I replied to your other thread. This just keeps on getting more and more interesting