2nd gen issues? Try this first!

[allmyEXes]

@Raph X. That could be a wiring or ECT sensor issue. Correct me if I'm wrong but there are two sensors there. One for the gauge and one for the ECM. Also a stuck open thermostat could be keeping the engine too cool but I think thermostats stay closed when bad. However if the thermostat was defective I think at some point the engine and radiator would "heat build" during the hot time of the year. Are you using more fuel than you think that you should be? Is there a thermostat in the system or has someone previously removed it?

 

[cantornikolaos]

The Trans connector was the cause of my alternator issues.

And very likely the cause of the all the codes, O2 sensors, I was getting.

So 2 O2 sensors, 2 coil packs, 1 alternator, about 30 hours, and a lot of swearing could probably have been avoided.

I found mine was loose while tracing back the green/red wire.

After separating the connector, I sprayed both pieces with MAF cleaner, it was sitting right there, let it dry then put it together and snugged the bolt up.

The alternator issue went away immediately, and all residual rough running smoothed right out.

Live and learn, remember Occam's Razor!

Where is the trans connector?

 

[MAS Tequila]

This is it, on the firewall.

 

[Balke]

@Raph X. That could be a wiring or ECT sensor issue. Correct me if I'm wrong but there are two sensors there. One for the gauge and one for the ECM. Also a stuck open thermostat could be keeping the engine too cool but I think thermostats stay closed when bad. However if the thermostat was defective I think at some point the engine and radiator would "heat build" during the hot time of the year. Are you using more fuel than you think that you should be? Is there a thermostat in the system or has someone previously removed it?

The new thermostat that i installed , will stay open when it goes bad . At least that is what the part info says.

 

[Jsck5466]

Sometimes a gremlin can be caused by the smallest thing.

There are 2 large wire bundle connectors on the firewall. Both are held tight with a 10mm bolt.
Any bad connection in either plug can cause just about any issue. from bad transmission shifting, bad o2 sensor readings, no start, no power, etc.

Right above the HVAC blower motor is the PCM connector.
View attachment 98220
Above the intake manifold is a large square black connector. This is the main harness for everything electrical and transmission related from truck to main wire harness. Trans harness for short. It also has the 02 sensor wiring because they run down along the transmission.
View attachment 98221

since this cost nothing, and can cause a lot of issues, the first thing in your troubleshooting should be to loosen these connectors, look them over for bent or pushed back pins, and then if all looks good, re-seat them and tighten the bolt.

If this does not help you, well, keep digging in the forum for an answer.
If it does, please post in this thread so we can keep track.

Thanks, and good luck!

hello and i am a new member with issues concerning my ongoing attempt to finish my work on a 97 explorer AWD 4404 tc & 4r70w tranny. it started with a TC chain replacement .. got that done .. had a rear main issue so i replaced that.. when i finished putting tyranny back on and started it it threw 743 ,750, 765 codes yelkes! and the o/d off light is flashing !!! being a Dumb dumb i jumped right to it and replaced the tcc and shift solenoids .. filter.. and guess what the codes are still showing up .. So now any pacific thing anyone could point out to we're i should start with 1st.. electrical connections . glad i saw your write up thks and help please jack

 

[Balke]

hello and i am a new member with issues concerning my ongoing attempt to finish my work on a 97 explorer AWD 4404 tc & 4r70w tranny. it started with a TC chain replacement .. got that done .. had a rear main issue so i replaced that.. when i finished putting tyranny back on and started it it threw 743 ,750, 765 codes yelkes! and the o/d off light is flashing !!! being a Dumb dumb i jumped right to it and replaced the tcc and shift solenoids .. filter.. and guess what the codes are still showing up .. So now any pacific thing anyone could point out to we're i should start with 1st.. electrical connections . glad i saw your write up thks and help please jack

Ok , im not Mr. Joe Pro ,, but I do know that the ATRA ( Auto. Trans. Re builders Assoc. ) said that you should start with the power and grounds supplied to the computer . I dont know if the codes are the same for yur trany as they are for the 4r44e family , but if they are , then i have the material info for every code that there is .

 

[Jsck5466]

Ok , im not Mr. Joe Pro ,, but I do know that the ATRA ( Auto. Trans. Re builders Assoc. ) said that you should start with the power and grounds supplied to the computer . I dont know if the codes are the same for yur trany as they are for the 4r44e family , but if they are , then i have the material info for every code that there is .

10-4 much appreciated sir. i'll let u no how it goes

 

[Jsck5466]

10-4 much appreciated sir. i'll let u no how it goes

ps does the overdrive button have issues

 

[Balke]

ps does the overdrive button have issues

Im not sure , but it might . My O.D. Button sometimes does not work , all i have on that , is info in how to service , replace it , but nothing about how it may cause the light to flash . , Anyway , your light is most likely flashing because of the codes that are popping up , whether or not your codes relate to real malfunctions , or if it is the computer that is just thinking that .
P.S. , i have the flashing light from hell also , it is intermittent , and the code is a PO741 TCC stuck off , it is one of the most common problems and mind boggling .!! I did some stuff, and so far , my trany improved amazingly big time , but my light still flashes ,...intermittently . There are many different reasons for the PO741 .

 

[Raph X.]

@Raph X. That could be a wiring or ECT sensor issue. Correct me if I'm wrong but there are two sensors there. One for the gauge and one for the ECM. Also a stuck open thermostat could be keeping the engine too cool but I think thermostats stay closed when bad. However if the thermostat was defective I think at some point the engine and radiator would "heat build" during the hot time of the year. Are you using more fuel than you think that you should be? Is there a thermostat in the system or has someone previously removed it?

Sorry a year late. Have been buisy. Thermostat was the fault. I just kept second guessing myself. I swapped it and shes been great ever since. Thanks for the info.

 

[Mbrooks420]

All thermostats are designed to fail open.

 

[dicksong]

Check this fuse if you have low voltage from your alternator. It's the main fuse for the power distribution box under the hood. There is a small cover behind the box that you flip down to find it.

It gets corroded and causes issue with starting and power.

View attachment 178207

View attachment 178208

View attachment 178209

I have had to do this twice, these pictures are from 5 years ago.

What is the part name and number?

 

[dicksong]

Sometimes a gremlin can be caused by the smallest thing.

There are 2 large wire bundle connectors on the firewall. Both are held tight with a 10mm bolt.
Any bad connection in either plug can cause just about any issue. from bad transmission shifting, bad o2 sensor readings, no start, no power, etc.

Right above the HVAC blower motor is the PCM connector.
View attachment 98220
Above the intake manifold is a large square black connector. This is the main harness for everything electrical and transmission related from truck to main wire harness. Trans harness for short. It also has the 02 sensor wiring because they run down along the transmission.
View attachment 98221

since this cost nothing, and can cause a lot of issues, the first thing in your troubleshooting should be to loosen these connectors, look them over for bent or pushed back pins, and then if all looks good, re-seat them and tighten the bolt.

If this does not help you, well, keep digging in the forum for an answer.
If it does, please post in this thread so we can keep track.

Thanks, and good luck!

How long should it take the CEL to come back on after doing this? removing the battery and/or these 2?

 

[Turdle]

How long should it take the CEL to come back on after doing this? removing the battery and/or these 2?

Could you please rephrase this? CEL should not come back on unless there is an issue so your question, the way it is worded has me confused. Which 2 what?

 

[Postal_Dave]

There are several of these connectors under the hood. The 4.0 has one on top of the air intake manifold, then there are 3 more under the main fuse box, on the firewall.

 

[Blandy]

I'll have to check these on my sons Explorer. It has a random no start issue after being driven and then shut off once in a while. Not often, but still a pain in the ass when it happens. After the truck sits a while (1-2 hours) then it'll start again.

I got the same problem with my 95 4.0. Did you fix it?! How?

 

[Mbrooks420]

I got the same problem with my 95 4.0. Did you fix it?! How?

Coolant temp sensor. The one for the ECU, not the gauge.

 

[Blandy]

Coolant temp sensor. The one for the ECU, not the gauge.

Are you kidding me? The coolant temp sensor kept it from STARTING?! I would think that near impossible.

 

[Mbrooks420]

Are you kidding me? The coolant temp sensor kept it from STARTING?! I would think that near impossible.

You may think anything you wish.

 

[Fix4Dirt]

Are you kidding me? The coolant temp sensor kept it from STARTING?! I would think that near impossible.

yes sir the amount of fuel used will depend greatly on the coolant temp. it may think its overheating etc on starting.it could have too much or too little fuel