2006 jeep commander transmission control module location

Jeep Grand Cherokee (2008) 3.7L

Had the ignition switch recall done in 2017. Not sure if it is related to the current issue or not just figured I would add that bit of info.

Transmission over temp light came on when first cranked (it has been below freezing here in NC when the light came on)

We have HUM hooked up to the jeep and the following codes were kicked:

U0101 Lost communication with TCM
P0605 PCM Read Only memory error

The PRND are all lit up on the dash
Stuck in limp mode, wont go above 25 mph

Dealership says we need new Transmission Control Module. Will cost 900$ to purchase part and Labor to put it in.

If any of you fine folks could please tell me (images if possible) the location of the TCM (2008 Grand Cherokee) that needs to be replaced. I would like to replace it ourselves and try to save some $. Any help would be greatly appreciated.

There is no separate TCM, it is built into into the PCM/ECM (whatever you want to call it). There is a separate shifter control module below the shift lever which may be your problem. Sometimes they can be dis-assembled and cleaned. I did mine nearly 10 years ago and its still working fine. See You-tube for DIY videos or search here on JF.

Not true for the 3.7's and 6.1's. The 3.7's and 6.1's have the Mercedes NAG1 transmission and the TCM is separate from the PCM on them. It is located under the dash right around (probably right side) the steering column. As far as the replacement goes, you can buy them for around $200-300 and that's for the Mopar Performance version.....may only work on the sedans though. I would think you could find a stock one for around $100 or so. I have one of the Performance ones in my Hemi LX......makes the transmission work completely different. Do a search for, "Jeep 3.7 Transmission Control Module" and see what comes up. These things rarely fail, but can "accidently" be reprogrammed with tools like the Starscan. They control the shift schedules, torque management, and contain the differential ratios installed in the vehicle. They're also easy to replace....two plugs.....maybe a half hour job, with the hardest part being the removal and replacement of the lower dash cover. You'll probably need to do a relearn too, if you replace it.

The "lost communication code you've received can be caused by simply disconnecting the battery. I'd start by clearing the codes and see if they return. You may also want to check the plugs on the PCM for cleanliness, security, and proper connections. The brackets around the gear positions could very well be the shift module Nejeep alluded to. Does the transmission appear to work properly?

What is Starscan? Is that what they use to reprogram the ignition switch when the recall work was completed?

I checked the PCM and all of the connectors and it was all clean and dry.

The transmission was fine until it went into limp mode. Now it wont come out of 2nd gear.

Both codes kicked at the same time (prior to disconnecting the battery). We did remove the battery and had the charge tested... battery is working fine. It is only 2 years old.

When it comes to the TCM how do you know it is broken vs a possible reprogramming? I am worried the dealership knows it can be reprogrammed and is just telling us we need a new one. Along with the cost of a few hours of labor. The TCM is a computer board essentially? So it would not have an outward sign of being broken or having failed, correct? Not sure if they are basing this solely off of the code of U0101 (lost comm w/TCM) or some other factor.

What is Starscan? Is that what they use to reprogram the ignition switch when the recall work was completed?

I checked the PCM and all of the connectors and it was all clean and dry.

The transmission was fine until it went into limp mode. Now it wont come out of 2nd gear.

Both codes kicked at the same time (prior to disconnecting the battery). We did remove the battery and had the charge tested... battery is working fine. It is only 2 years old.

When it comes to the TCM how do you know it is broken vs a possible reprogramming? I am worried the dealership knows it can be reprogrammed and is just telling us we need a new one. Along with the cost of a few hours of labor. The TCM is a computer board essentially? So it would not have an outward sign of being broken or having failed, correct? Not sure if they are basing this solely off of the code of U0101 (lost comm w/TCM) or some other factor.

The Starscan is a Chrysler diagnostic/programming tool used by dealers for updates, programming, diagnosing, etc. the various computer modules in our Jeeps. There are now aftermarket tools that have the same capability. I don't know whether they needed to use it when doing the recall, as I have not, and won't ever have this recall done. I do know that a lot of stuff comes off the ignition switch, so if they damaged the wiring harness/plug or the switch is bad, there could be electrical problems. By the way, the TCM is probably fairly close to where they were working and I am sure they had to remove the lower dash cover to get to the switch. I suppose, if the TCM is located close to the switch, they could have done something, but they would have to had to work at it, as the plugs are pretty well protected. If you want, you could remove the lower dash cover under the steering column and check the plugs on the TCM (TCM is not very big and the plugs are side by side...2 of them), and the ignition swtich plug(s) for security. The TCM is about 3X3 in. (or so) and maybe 3/4 in. thick and the plugs have quite a few wires going to them.

A good computerized diagnostic tool should be able to tell whether the TCM is functioning properly, but probably not whether it's been reprogrammed. I have both an Autel DS708 and MS906 tools and the MS906 has 22 functions it can accomplish on the TCM portion of the 545RFE transmission in my Jeep.....probably about the same on the NAG1. I think the first thing you should do is resolve the bracketed shift lever position issue, as this can cause DTC's and Limp Mode. Also, clear all codes first and see if it will work properly.....at least until or if it sets the code(s) again.