2006 Ford Explorer - Trans Codes

[Ruger77]

We have a 2006 Ford Explorer in for "trans codes". Customer complaint of trans shifting weird, etc.. I could not really duplicate any kind of symptom, other than 3 memory codes in the trans computer. They are U0100 (lost communication with ECM/PCM), U0121(lost comm. w/ABS control module), U0102 (lost comm. w/transfer case module). These codes have all been cleared and return, but are never "hard codes" . I have checked the CAN circuit (2 wires) from the ECM & TCM to ALDL connector and to each other all at .8 and .9 ohms. This seems to me to be a potential wiring problem on the CAN circuit, but I can't figure out what connector or harness these all have in common. Pins at ECM and TCM connectors look good. Scan tool communicates with all modules all the time. Since the Trans. Control Module is the only one losing comm. with the other modules, and they aren't losing communication with it, is it likely that the TCM is bad? EX: If the trans loses communication with the ECM, why don't I have a ECM code for lost communication with trans. All self tests pass, and no other systems ever get these memory codes except the trans. I hope this makes a little sense. Any help appreciated. Another shop told this customer (after they looked at it) to take it to a dealer, but it came here instead.

[ricmorin]

Yeah, it makes sense. I'd monitor the can line with a scope. See if it goes to ground or voltage. I'm suspecting that it does intermittently. Then it's a search and destroy mission. Either the circuit is shorted by a rub through, or one of the modules is pulling it down. These can be fun.

[Tim Martin]

Depends on yer definition of fun.

At times this type of situation needs only a TCM/PCM/ECM reflash. Otherwise, as noted, diagnosis can be, well fun hardly describes, at least by my definition. Challenging is the word I use. Only thing I'd mention, make sure ya got the proper tools for diagnosis. Otherwise you may be led to a faulty conclusion or otherwise damage these supposedly delicate electronic devices.

Good luck.

[Ruger77]

Thanks for the replies..... I agree on the possible reflash & scoping these circuits. If I understand the CAN circuit correctly, the modules can lose their "addresses" , therefore their ability to communicate with the other modules on the network, in the event of a possible ground / power loss, or some other similiar event. I think scoping the CAN circuits at the TCM is my next step. I'm trying to sell more diagnostic time, but if customer leans toward the dealer, I might let it go. I hate to see that, but it might be smart business. (Sure wish I had the ability to reflash... just in case).............Dear Santa.....

[steven kiser]

for some reason i'm seeing a boat load of rub throughs......on ford trucks i'm seeing many rubbing through where the harness runs down the inner fender on the drivers side.

[ricmorin]

Which engine? The data lines are different.

[Ruger77]

Ours is a 4.6L.

[Ruger77]

OK, just an update. Scoped CAN wires at trans and no spikes while driving...... however, no codes have come back either. I'm not sure if I improved a connection when OHM testing, or moved a harness near a rub point, or what, but can't duplicate complaint now. Anyway, customer has vehicle now, and they are going to dealer if it acts up again. Customer is a regular, so they are supposed to keep me posted as to the outcome.....I'll share the results here. How do you guys handle billing for these situations, not $$$ amounts, but billable hours? I have always thought of them as customer satisfaction/training sessions, and bill a small portion of the hours invested. I document all we've done, but I find it hard to bill all of the time, when I don't think it's repaired or diagnosed.

[brianp87]

If I fix the problem I charge all the time i can get

[steven kiser]

your absolutely correct on your feelings about charging in situations like these especially if you can't be 100% sure it's fixed. when i have an "i'm not sure" if i fixed it or not, it's a crap shoot. it's handled on a situation to situation. now on the other hand and this being a technological business i take pictures of the progress. the first series show their vehicle so they know it's theirs. i had a truck in the shop and i was the fourth shop it was in. an evap code kept popping up. the canister and all valves had been replaced and not professionally. we took pictures of the repair. we traced the problem to a harness rub at the lower lip of the inner fender. took a picture of the area. it was a dump truck so a harness removal was simple. we felt it necessary because we had a feeling that the harness was uses as a pin cushion. we were right. ordered a new harness and was able to show the customer where all the (or enough to satisfy him) pin holes in the harness were and he understood why we replace it. we had re-routed the harness so it wouldn't rub through again. pictures enabled us to get what it was worth. at least that's how i feel. it showed the progress and the end result. customer knew we didn't go right to the short and had it fixed in 10 minutes. it was like they were there. i've told people that i get what i get and it's fixed. what was spent prior to coming here is of no consequence to me. i've looked at harnesses and my mouth has dropped. scotch locks, non weather proof splices, incorrect gauge splices, unsecured and open harnesses, swollen pierce points, etc. these situations are ones that make it necessary for me to travel to a favorite salvage yard on a saturday and pay the 5$ entry fee and strip a harness. well enough for me, my first replay and i'm feeling a bit gabby.............