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08 Explorer w/ 5R55S Issues

CRex619

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08 Explorer Eddie Bauer
Good Evening Everyone,

I'm going to try to make this post as detailed as possible so I don't miss anything.

I recently purchased a 2008 Explorer 4.0L Eddie Bauer Edition with a known blown head gasket. I've since replaced the head gaskets (and the heads) reassembled everything and have found it also has transmission issues (yay!). When I was rebuilding the engine I replaced the radiator, so I lost a little transmission fluid when I removed it. After replacing the radiator one of the cooler lines going into the radiator developed a leak so I had to replace that. I ordered a replacement line from Rock Auto and cut the existing line, and put the flexi rubber hose in it's place. Got everything hooked back up, got the car up to temp and topped off the fluid. Went through each gear just in case the PCM needed to relearn anything. Immediately noticed hard shifting into reverse and a slight jolt when shifting into D. I figured this may be the transmission relearning everything so I took it for a test drive. Once in reverse, it works wonderfully, no slipping, just the initial hard shift. Then I shift into drive, it seems like it's stuck in 3rd gear (limp mode?) and won't even attempt 1st or 2nd. I can't even get it to manual shift into 1st or 2nd (can manual shift into 3rd no problem) to keep the car moving at speed it feels like I have to have the pedal depressed fully, if I fully depress the pedal the power kicks (if at or above normal 3rd gear operating rpms). I do have a slew of codes I was able to pull.

P0743
P0755
P0760
P0962
P0966
P0970
P0740
P0748
P0758
P0763
P0778
P0798
U2023

Perhaps it could be the solenoid pack? Fluid flush/fill? Valve body? External Solenoids?

I don't want to start dumping money into replacing things that don't need replaced. Car has 204k miles on it, and it LOOKS like the trans has been replaced at some point so I'm going to hazard a guess that the transmission may have more or fewer miles on it.

Any/all help is appreciated!
 


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imp

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.... just the initial hard shift. Then I shift into drive, it seems like it's stuck in 3rd gear (limp mode?) and won't even attempt 1st or 2nd. I can't even get it to manual shift into 1st or 2nd (can manual shift into 3rd no problem) to keep the car moving at speed it feels like I have to have the pedal depressed fully, if I fully depress the pedal the power kicks (if at or above normal 3rd gear operating rpms). I do have a slew of codes I was able to pull.

P0743
P0755
P0760
P0962
P0966
P0970
P0740
P0748
P0758
P0763
P0778
P0798
U2023

Perhaps it could be the solenoid pack? Fluid flush/fill? Valve body? External Solenoids?.............

@CRex619

What are "external solenoids"? All 8 solenoids are internal to the transmission. Now, my Ford DTC listing for some reason has no entry at all for 5 or 6 of your codes, but the preponderance of them seems to be aimed at solenoid problems of all kinds, a truly difficult to imagine situation which could only result from faulty electrical connections, "cooked" wiring loom above the transmission adjacent to exhaust pipe, or a failed PCM. Now, need to know: Did you ever hear the engine run, and if so, did you shift into gear(s) With what result? IOW, did the transmission issues already exist when you got the vehicle? I assume the wiring harness is indeed plugged into the solenoid connector externally?

U-2023 may be the most valuable clue here: one of the CAN bus connected modules is failing to respond with usable data. By 2008, several of those modules, notably the 4X4 Module, was built into the PCM. If in limp mode (sounds likely), a code would be thrown saying "Forced limited Power". Since that's not seen, it seems limp mode is unlikely.

With my own limited understanding here, if it were me, I would check condition of all the wiring, including connectors, between the transmission and the PCM. If no obvious fault is seeable, I would get out the wiring diagrams, separate the harness wiring at both transmission and PCM, and proceed to check electrical resistance beginning with the most obvious: the one(s) feeding power to the solenoids, then returns to the PCM. No anomaly found, I would seriously consider the PCM as trouble source and try replacing it.

Others here may have additional help here, for they know a helluva lot more than me. imp
 




CRex619

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That gives me a good starting point for sure! I appreciate it. I never heard it run prior to purchasing it, and wasn't made aware of any existing transmission issues. I've also noticed that when I push the O/D button nothing happens (not sure if it's supposed to or not, I imagine some kind of light should come on). Also went through and checked fuses in case that was the issue. With the program learning these newer cars have, is it feasible/easy to just swap out the PCM or does it involve some resetting of things?
 




transman304

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You have lost power to Transmission. Either a fuse or case connector that are known for corrosion and loss of connection. They have new external wiring harness with connector available.
 




imp

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That gives me a good starting point for sure! I appreciate it. I never heard it run prior to purchasing it, and wasn't made aware of any existing transmission issues. I've also noticed that when I push the O/D button nothing happens (not sure if it's supposed to or not, I imagine some kind of light should come on). Also went through and checked fuses in case that was the issue. With the program learning these newer cars have, is it feasible/easy to just swap out the PCM or does it involve some resetting of things?
@CRex619
When ign. key is first turned on, nearly all icons on instrument should light up. They turn off one by one as each function is checked for proper operation: ABS, Air Bags, etc. A few stay on until the engine starts, notably "Service Engine Soon", "BATTERY", "CHECK GAGE".

The "O/D OFF" light only illuminates with engine running, when the button is depressed momentarily. If left in "OFF" position, eng. shut-off defaults light back to not on, meaning it defaults to O/D ON each time the eng. is shut off.

"Program learning" of these cars is largely hocus-pocus aimed at guaranteeing no home-repairs of much anymore. We try our best to circumvent such dictator-like design tactics.

Certainly a PCM can be swapped out. Easy? Depends on how much knuckle-bruising you can stand. I replaced mine with no trouble at all. Needlessly, because my diagnosis was wrong. Don't go ahead and piss away money on a new one on my say-so alone. Get some other opinions. OTOH, that direction, given only the other option of transmission replacement, involves maybe 10% of the cost of a rebuilt transmission, assuming you can absorb the labor costs of installing the PCM yourself.

In the Ford Trouble-shooting Manual, many "issue-resolution" listings have "Replace PCM" as usually the last choice; they DO go bad (occasionally). Here's where I ordered mine:

Flagship One Inc | PCM | ECM | ECU | Engine Computer

Good luck! imp
 




imp

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You have lost power to Transmission. Either a fuse or case connector that are known for corrosion and loss of connection. They have new external wiring harness with connector available.
@transman304

:dpchug: Theory meets the guy who does such work daily! I only talk about it. Thanks! imp
 




CRex619

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You have lost power to Transmission. Either a fuse or case connector that are known for corrosion and loss of connection. They have new external wiring harness with connector available.

Oh if only you were closer! I live about 2 hours from you. I'll give it a look over and see what I can find out.
 




CRex619

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So an update (sort of)

To make sure I'm checking this properly, I took the fuse out labelled 38 (15a) and put my multi-meter on one side of the connector, then on the other while maintaining a ground. I tried with the key in the on position, and with the car running and I can't get any juice whatsoever. My question, am I checking the right fuse? What should the output be? Does it have be checked in a certain way? What could be disconnected? Bad relay?

64358589_422612398320769_3283903974154960896_n.png


64542224_622339644932174_5509330854691733504_n.png
 




transman304

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May want to check the PCM relay for power in and out.

A92DF3D2-1940-4AE1-B42B-980DD1431375.png
 




imp

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I took the fuse out labelled 38 (15a) and put my multi-meter on one side of the connector, then on the other while maintaining a ground. I tried with the key in the on position, and with the car running and I can't get any juice whatsoever. My question, am I checking the right fuse? What should the output be? Does it have be checked in a certain way? What could be disconnected? Bad relay?
Not clear what you are attempting to do. A blown fuse generally is visibly detectable. If unsure, use OHMMETER across fuse terminals (removed from fuseblock). Good fuse = 0 ohms. Blown fuse = very high, open circuit.

If you are attempting to check whether power is reaching that #38 fuse position, see @transman304 's diagram. Fuse 38 is fed by the PCM Power Relay, then feeds Solenoid at very bottom of diagram.
 




SparkyF250

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2005 Explorer XLT
Good Evening Everyone,

I'm going to try to make this post as detailed as possible so I don't miss anything.

I recently purchased a 2008 Explorer 4.0L Eddie Bauer Edition with a known blown head gasket. I've since replaced the head gaskets (and the heads) reassembled everything and have found it also has transmission issues (yay!). When I was rebuilding the engine I replaced the radiator, so I lost a little transmission fluid when I removed it. After replacing the radiator one of the cooler lines going into the radiator developed a leak so I had to replace that. I ordered a replacement line from Rock Auto and cut the existing line, and put the flexi rubber hose in it's place. Got everything hooked back up, got the car up to temp and topped off the fluid. Went through each gear just in case the PCM needed to relearn anything. Immediately noticed hard shifting into reverse and a slight jolt when shifting into D. I figured this may be the transmission relearning everything so I took it for a test drive. Once in reverse, it works wonderfully, no slipping, just the initial hard shift. Then I shift into drive, it seems like it's stuck in 3rd gear (limp mode?) and won't even attempt 1st or 2nd. I can't even get it to manual shift into 1st or 2nd (can manual shift into 3rd no problem) to keep the car moving at speed it feels like I have to have the pedal depressed fully, if I fully depress the pedal the power kicks (if at or above normal 3rd gear operating rpms). I do have a slew of codes I was able to pull.

P0743
P0755
P0760
P0962
P0966
P0970
P0740
P0748
P0758
P0763
P0778
P0798
U2023

Perhaps it could be the solenoid pack? Fluid flush/fill? Valve body? External Solenoids?

I don't want to start dumping money into replacing things that don't need replaced. Car has 204k miles on it, and it LOOKS like the trans has been replaced at some point so I'm going to hazard a guess that the transmission may have more or fewer miles on it.

Any/all help is appreciated!

My 05 did the same thing, every trans code came up, the trans shop was at a complete loss. Turned out to be the PCM
 




CRex619

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Just to provide everyone closure in the event anyone cares...:p

The problem ended up being the solenoid pack was shot. Replaced with a remanufactured one today and it shifts like butter.

Now to replace that pesky (noisy) wheel bearing (hub)

Thank you everyone for your insight.
 




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