Cat 143h missing gears

[Mason harris]

Transmission harness did not fix the problem.

 

[Nige]

Transmission harness did not fix the problem.

That's a bit of a bugger. Unless @ahart can think of a reason for replacing the harness "F" (143-3433) between the transmission and the ECM it appears as though the ECM is the culprit. As I said earlier it could be that the driver circuit for clutch #7 is failing but that is not what the -6 (connected) -5 (disconnected) Codes indicate.

There is a 10R-4332 Reman ECM available for OEM P/N 172-9389. It will probably be somewhere around 50-60% of new price, maybe $2.5-3k range, if you want to take a punt on a Reman. Whichever option the replacement ECM will be a blank box and will require flashing with the appropriate powertrain software for the machine Serial Number. I'm guessing that the dealer Parts Dept will have to involve the Service Dept to do that for them.

 

[ahart]

I’ll admit, the data on this one is very conflicting. But if we’re at an ECM and we are confident in the data that we’ve got, then we have little choice but to go that route.

 

[Nige]

My thoughts too. The -6/-5 Diagnostic Cdoe data conflicts with an ECM failure but there really appears to be nothing else left. IMO replacing the 143-3433 Harness would likely be throwing good money after bad.

 

[Mason harris]

Just to give a little more info I was able to get in it and run it today. When up shifting first second then third as soon as it hits third it will kick in gear for 1 second then the transmission light on the dash will go to flashing and it kicks out. I can shift straight to 3rd and it will kick in and stay in one time out of 6-7 shift.

 

[Nige]

So if I understand you correctly if you start in 1F and shift to 2F then 3F it takes 3F but then every time it kicks out after 1 second with the Transmission Fault light and a Code.

If you select 3F directly and take off it faults 6 times out of 7 but the one time it does hold 3F OK have you tried shifting up to 4F.? If so what happens.?

 

[Mason harris]

It does this same thing in every gear that uses the number 7 solenoid. When I get it locked in 3 as soon as I shift to 4 it codes out.

 

[Mason harris]

New ECM and she shifts just like she should.

 

[Nige]

New ECM and she shifts just like she should.

Glad to hear that. Did you go the Reman or new route.?

 

[Mason harris]

Customer wanted To go reman. Thank y’all for the help.

 

[Nige]

Thanks for the follow up. That one is surely going to get filed away for future reference because playing strictly by the diagnnostics book the FMI change from -6 to -5 when the #7 solenoid was disconnected indicated that the ECM was not the cause of the problem.

 

[Mason harris]

The guy and cat that did the ecm flash said he could see the code flashing. I guess in his break out harness. He said it was a pain to copy old config with it doing that.

 

[ahart]

Thanks for the update, definitely one of those I would have been nervous about putting an ECM on.

 

[Nige]

Thanks for the update, definitely one of those I would have been nervous about putting an ECM on.

I'll second that, especially based on the test results.
And having been on the wrong end of more than one transmission control valve harness failure over the years I was reasonably certain the harness was also the problem in this case.

I know ECMs do fail. Well obviously - this one did...........
But it's such a rare occurence these days unless someone's being doing something really stupid such as welding on one end of a machine with the ground cable attached to the other end, or trying to jump start a 24v machine from something 12v.

There's a reason why the last option listed for the possible cause of failure in any Diagnostic Code troubleshooting procedure generally states "The ECM has failed. This is unlikely." Often the procedure will tell you to repeat all the steps again if nothing else shows up, just because an ECM failure is such a remote possibility.

 

[ahart]

Agreed, I always assume that I must have missed something if I get down to the ECM being the problem. So we go through it all again, and again. Also on copying the old configuration files from old ECM to new ECM, cat doesn’t typically recommend using that feature, not so much on a failed driver as on a corrupt file, they say it’s likely that the old file could corrupt the new ECM. Was talking to the TC at cat a few weeks ago and now they’re recommending never downloading software from SIS over WiFi, they want it done over hardline only for the same reasons. Sure makes it hard on field service.

 

[JD955SC]

Agreed, I always assume that I must have missed something if I get down to the ECM being the problem. So we go through it all again, and again. Also on copying the old configuration files from old ECM to new ECM, cat doesn’t typically recommend using that feature, not so much on a failed driver as on a corrupt file, they say it’s likely that the old file could corrupt the new ECM. Was talking to the TC at cat a few weeks ago and now they’re recommending never downloading software from SIS over WiFi, they want it done over hardline only for the same reasons. Sure makes it hard on field service.

Cat needs to get their s*** together and they sure do love to come up with a billion reasons of “oh why you shouldn’t!!!!” To cover their B.S.

We have to download files over WiFi. Never an issue. And getting their copies of the original configuration files can be spotty. We copy the configuration and PSRs of every machine we PDI and attach it to the first work order so that helps some.

 

[Nige]

Think yourself lucky you're doing it today. Years ago the only way was to download flash files over an ethernet connection, store them on a floppy disk and take them to the job site with you. If you got really stuck you'd call someone back at the branch and have them download a file and email it to you as an attachment. The only challenge left at that point was to find someone you could hook up to an ethernet cable and download the file. I can recall many times in the filed gettng factory passwords over the phone with someone back in the office who could hook up to the system.
Happy daze .............

 

[Mason harris]

Ok in back with more issues with the same machine. Operator lost 5678 forward and 456 reverse. Already have new solenoids and a new harness and reman ecm. No codes this time. I’m getting 1.7 volts to the D solenoid bottom out side but never getting 24. Check at pin 11 at ECM and still just getting 1.7volts. When I unplug it I get a code. When hooked to ET it shows the shifter abs gear to both be in the right gear but won’t move.

 

[Nige]

I'd suggest two things.
1. First re-flash the software into the ECM. I've seen cases of "missing" bits of software that caused ECM's to act screwy before now. Only two things control the output of the 24v on whatever pair of pins it is for each solenoid; the ECM hardware/internal wiring, and the installed software.
2. If the previous step doesn't fix the problem I think you're in for another ECM. Seeing as it only laste a month it's known as "infant mortality". It happens occasionally.

I'd like to hear what @ahart thinks........

 

[Mason harris]

Is the bottom outs side solenoid the right solenoid for the gears missing? Dealing with these solenoids is kinda a pain. Some say solenoid d or 4 but it run clutch 8 I think and the wiring diagrams are weird too.