1996 Ford Explorer Transmission Shift Solenoid Issues

First, I want to say hello! First time Registering. Love this site, and has always been extremely helpful!

I have a Transmission Solenoid problem. First, I was getting an error code of P0751 for Solenoid SS1/A. I replaced the whole harness and Solenoid A and car worked for a little while.

My check engine light came on again and I did another diagnostic and received a code P0761, which is the SS3 solenoid or Solenoid "C". When I got home, I did another diagnostic on now received a 2nd error code of P0751, Solenoid SS1 or Solenoid A. So, now I am a little confused. Can One solenoid affect the other? Could Solenoid C have gone bad and then affect Solenoid A or vice versa? I never previously had a Solenoid C issue, only A, now I have them both after a full harness install.

Both Solenoid C and A are replaced, but received same error codes again when driving about 400 miles, first P0761, then P0751. I thought maybe it was the PCM, so I replaced the PCM, and it worked for awhile, then bam, I am getting the same errors, so I do not think it is a PCM issue.

I do not think it is the PCM Power Relay, but I could be wrong. I know I can test the voltage on the Solenoids, to see if they really are bad, correct? Or is there something else that I may be missing, connection from the harness to the PCM perhaps or something else? I checked all fuses, great, all relays work, but I never did test them, just visual. Is there something I can do to do further testing? Anyone know if I am missing some steps here or looking in the wrong direction?

I think you have done the right things so far, checking solenoid resistance from the PCM connector to transmission could be helpful.

Is the transmission working like it should and you are just getting the light?

No flares? Slips?

I have seen blown valve body gaskets cause solenoid codes, but the trans usually slips or flares or something else is wrong also.

JK080 said:

I think you have done the right things so far, checking solenoid resistance from the PCM connector to transmission could be helpful.

Is the transmission working like it should and you are just getting the light?

No flares? Slips?

I have seen blown valve body gaskets cause solenoid codes, but the trans usually slips or flares or something else is wrong also.

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The Tranny doesn't slip, but it can shift hard (because it is the shifting solenoid not working correctly) and it will RPM in the 3k's when going 65-80 MPH (after 80 it is smother, but when going between 65-80, it runs rough.) and will clunk when I stop once in awhile. The Transmission has been rebuilt, but it is not the tranny, as I have had numerous mechanics look at it and they say it is an electrical issue, which is what I am trying to pinpoint to no avail. Also, I have not really had any flares, it does, when the solenoid does the check engine not have power when going from stop to 2nd gear, but once I reset the PCM, that goes away. It is definitely something electrical I think. I am not sure if I am missing something in my troubleshooting. I replace the PCM relay, no change. I ordered a Solenoid C (SS3) and will install.

I do not have a blown gasket, all of that checks out fine.

Also, can a solenoid affect another solenoid? I know SS3 and SS1 are right next to each other, not sure if that is a reason they are both failing.

How do I check the solenoid resistance? What are the resistance ohms? 20-25 or something? I can look it up, but I have never checked the resistance on the solenoids before, I have used the multimeter to check everything else. Thanks for the response!

Only thing the two solenoids have in common is the harness. I can't see how one is effecting the other but I think they might share the same problem.

The resistance for shift solenoid 1,2,3 is 22 - 48 ohms

The TCC solenoid should be 8.9 to 16 ohms and the EPC solenoid is 3.1 to 5.7 ohms.

JK080 said:

Only thing the two solenoids have in common is the harness. I can't see how one is effecting the other but I think they might share the same problem.

The resistance for shift solenoid 1,2,3 is 22 - 48 ohms

The TCC solenoid should be 8.9 to 16 ohms and the EPC solenoid is 3.1 to 5.7 ohms.

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22-48 ohms, excellent. How do I test the resistance for the solenoids?

JK080 said:

Only thing the two solenoids have in common is the harness. I can't see how one is effecting the other but I think they might share the same problem.

The resistance for shift solenoid 1,2,3 is 22 - 48 ohms

The TCC solenoid should be 8.9 to 16 ohms and the EPC solenoid is 3.1 to 5.7 ohms.

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Ok, I tested solenoid "A", and it give 26.8 ohms and Solenoid "C" says 26.6 ohms. Those are both within the ohms parameter. Now when you say resistance testing is this what I was testing or am I testing the air flow or something else? I can get a 9V and test the mechanism itself and see if it clicks. Either way, both Solenoids are good, should I now check the wiring to the pcm or the harness itself? Also, I checked solenoid "B" and it is fine too.

If you ohm the solenoid from the PCM connector you will check the wiring and the solenoid, its a good way to check for poor connections or shorted wiring.

You can also check individual wires if you ohm them from one end to the other end, obviously you will want ohm readings of the wire right at zero.

The computer controls the ground for each solenoid, you will want to find the power wire for the shift solenoids and then check each shift solenoids ground wire for the ohms at the PCM connector.

Note: The EPC and the TCC will have their own 12 volt power wires, also all three power wires at the case connector are red.

JK080 said:

If you ohm the solenoid from the PCM connector you will check the wiring and the solenoid, its a good way to check for poor connections or shorted wiring.

You can also check individual wires if you ohm them from one end to the other end, obviously you will want ohm readings of the wire right at zero.

The computer controls the ground for each solenoid, you will want to find the power wire for the shift solenoids and then check each shift solenoids ground wire for the ohms at the PCM connector.

Note: The EPC and the TCC will have their own 12 volt power wires, also all three power wires at the case connector are red.

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How do I check the ohms in the pcm? I have never done that before.

You don't check the ohms of the PCM, you disconnect the harness from the PCM and check the wires going to the transmission.

JK080 said:

You don't check the ohms of the PCM, you disconnect the harness from the PCM and check the wires going to the transmission.

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Is it a visual check? I am not sure what you mean by check the wiring when I disconnect the harness from the PCM. Do I use my multimeter to check the current? Is it a visual inspection? Can you please give me a process or step by step of what I should do specifically?

The ignition works a relay in the power distribution box, this relay will supply power to all three red power wires for the transmission. Remove the relay and find pin 30, I don't know which one it is but you should be able to figure it out.

You should connect one lead from the DVM to this wire in the box and use the other lead to check the ohms for the transmission solenoid pins in the PCM connector.

Here is the distribution box with the Power Relay, I think its located on the right hand side fender area...maybe



Here is the PCM connector

SS1 is pin 27
SS2 is pin 1
SS3 is pin 53

TCC is pin 54
EPC is pin 81

You may have to use a paper clip to get into the connector, be careful not to damage the pins. You should end up with reading close to what you have already found. With the meter connected you may want to pull on the harness to see if you loose connections.

Excellent, thanks for the diagrams. DEFINITELY HELPFUL!

In the PCM Power Relay, I am using the 30 pin slot to connect to with my multimeter and then connecting to the 53 pin of the pcm wire harness with the other wire to the multimeter, correct? I should then get the similar ohms of 26.8?

Also, the PCM wire harness is grounded next to the pcm, I need to disconnect this to test it, should I reground it or is it ok to leave ungrounded?

Correct, you should be close to your previous ohm readings. If they are high readings there is resistance in the wires from a bad connection or bad wire condition ect.

You can leave the grounds connected, but I would disconnect the battery before removing the PCM connector.

JK080 said:

Correct, you should be close to your previous ohm readings. If they are high readings there is resistance in the wires from a bad connection or bad wire condition ect.

You can leave the grounds connected, but I would disconnect the battery before removing the PCM connector.

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I did the test, and all solenoids are 27.2 - 27.7, so it is not the solenoids in regards to what the test says, correct? I do not know what else to look at or what else it could be. Do you have any other ideas that could point me in the right direction? You have helped me so much, it is really appreciated!!!!

If this is a intermittent problem the problem still may be in the harness, maybe do the same test just after it sets the code for one of the solenoids. Heat may play a part in this, as heat goes up so does the resistance. Also pull on the wire harness with the meter connected to see if you get any changes.

Clean all ground wires, remove them if you can and clean the surface under them.

JK080 said:

If this is a intermittent problem the problem still may be in the harness, maybe do the same test just after it sets the code for one of the solenoids. Heat may play a part in this, as heat goes up so does the resistance. Also pull on the wire harness with the meter connected to see if you get any changes.

Clean all ground wires, remove them if you can and clean the surface under them.

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It is a continuous problem, I have to reset the PCM in order to get the Explorer to run somewhat decent. but once the check engine light comes on, then it starts to shift a little harder, rpms high (3k+) when going 65-80 mph. . I will test again on the PCM harness and give a little pull to see if anything changes. Should I take the internal tranny harness off with all of the solenoids and check all wires and connectors as well?

Is there anything else that can be causing this? I have two PCM'S, i do not think they are both bad, but should I try another PCM?

I dont think its the PCM since you have swapped it already and I don't see them causing problems on the ones that I work on, or do I see harness problems and even a failed solenoid is not that common and you have replaced them already. You said the valve body gaskets are good and you have replaced the internal harness. You could check the servos and bands or the valve body. Going back over the internal harness again and moving solenoids around are things you still can do if like, maybe something will pop up. I did a search in a couple of big data basis for those two codes and didn't really come up with anything much or that you haven't already tried.

After what you have done with diagnosing already I am beginning to lean more towards a transmission problem rather a electrical problem. I know its setting solenoid codes, lots of cars set solenoid codes and its really internal issues.

Scanners with a decent data stream and control boxes that allow you to take control of a transmission electrically are important tools used to help determine which way to go with things like this. Maybe you can find a shop that has one and knows how to use it if you continue to come up with no solution.

JK080 said:

I dont think its the PCM since you have swapped it already and I don't see them causing problems on the ones that I work on, or do I see harness problems and even a failed solenoid is not that common and you have replaced them already. You said the valve body gaskets are good and you have replaced the internal harness. You could check the servos and bands or the valve body. Going back over the internal harness again and moving solenoids around are things you still can do if like, maybe something will pop up. I did a search in a couple of big data basis for those two codes and didn't really come up with anything much or that you haven't already tried.

After what you have done with diagnosing already I am beginning to lean more towards a transmission problem rather a electrical problem. I know its setting solenoid codes, lots of cars set solenoid codes and its really internal issues.

Scanners with a decent data stream and control boxes that allow you to take control of a transmission electrically are important tools used to help determine which way to go with things like this. Maybe you can find a shop that has one and knows how to use it if you continue to come up with no solution.

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I understand that, but I had this issue before the tranny was rebuilt and I have the issue after the tranny was rebuilt. So I am confused on how it could be the transmission itself. Also, I received another error code P0753, which is solenoid "A" again, so I get P0751, P0761 and P0753. Isn't that a bit odd? Also, I read this in another thread here, what do you think?

Same code, same car I experienced. '96 Exp Sport; P0761; no OD. I replaced the SS3, with no change. But I licked it. The code shows up when, after activating SS3, the PCM does not detect the reduction in RPM's associated with proper function. So, a mechanical cause can be the culprit. How to fix? Move the heat shield away from the OD servo port. Take the circle clip out of the servo port hole. This can be hard because the catalytic/exhaust is in the way, you only have about 1.5 inches to work with. Spray liberally with WD40 or gumout. The servo cover will probably be gunked in there because the cause of the problem is heat. Take the OD band adjusting nut and adjuster out. Take the nut off the adjuster. Put the adjuster back in and tighten it until the servo cover pops out enough for you to grab and twist it out. Take out the servo piston and spring. Eureka! The piston's rubber lips are hard as granite and razor sharp, causing the piston to stick in the servo cylinder most or all the time. So: either replace the piston, or, do what I did: take a 200 grit sandpaper and smooth the sharp edges all around, only about .2 mm, enough to make it dull (not sharp) on both bearing edges. Check the bore surfaces for crud, cleaning them with fine steel wool if necessary. Put it back together but first take out the band adjuster. Reinstall the spring and piston and cover and clip. Install the adjuster all the way, then back it off 1.25 turns. Install the jam nut. Reset the shield. You just saved a $1200 rebuild.

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Perhaps this is my issue? I asked him to give more specifics, as I have never done what he states and he has not gotten back to me, but maybe it will fix my issue?

Red_Lion said:

Perhaps this is my issue? I asked him to give more specifics, as I have never done what he states and he has not gotten back to me, but maybe it will fix my issue?

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Sure I believe that to be more of a realistic failure rather than a electrical fault. I believe your next step is in that direction, servos, valve body, bands.

JK080 said:

Sure I believe that to be more of a realistic failure rather than a electrical fault. I believe your next step is in that direction, servos, valve body, bands.

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Awesome, only issue, I have no idea what he is saying. The only thing I have ever done was replace the solenoid harness and install solenoids. Is there a step by step in how to do this? Maybe visuals so I know what I am looking at and what I am doing. I have no problem doing it, I just want to make sure I do it correctly and properly.