Hi all. Just joined up. Picked up an 02 Dakota SLT with 50K miles on it a few weeks ago. Complete with a nearly new plow. Service 4WD light has been on for a while. No 4wd, no lights on the switch, etc. Tested the switch and it seems fine so I went ahead and tore the dash off and pulled out the TCCM. What a freakin ordeal that was. Thankfully i found that link to the 01 service manual and downloaded that. Still a couple hours though. Couldn't find the part at Auto Zone or Advanced Auto. Called the dealer and they want $400 for it. Has anyone found it anywhere cheaper. I don't mind biting the bullet and paying the $400, but not if it is available cheaper. Thanks.

 

Odds are, its probably not the TCCM. If you got the service manual, check all your powers and grounds going to the module. Its actually more common for the CTM to fail. The thing is, the TCCM gets ignition switch info (on, off, start, run, etc.) over the communications bus rather than a hard wired voltage. If the CTM fails to send the igntion switch message to the TCCM, you will get the problem you describe. I would take your truck to the dealer, or if you have a friend with a DRB, and check the codes. It means paying diag fees, but its the only way to know what will fix it.


Oh, and welcome to the forum!

 

Thanks for the welcome and the reply man. DRB? Are you speaking of an OBD scanner, cuz there were no codes thrown. There are 2300 pages in that service manual. I can't even find the section to troubleshoot the TCCM voltages. Thanks.

 

DRB is Chrysler's special scan tool. It plugs into the OBD2 port, but does a TON more than a regular scanner. That's how the dealer can run all different types of tests and diagnostics. (They cost like $6,000! However, Toyota's thing is called Techstream, and basically the Toyota is a Toughbook with special software, which costs $8,000)

For wiring, you need to look at section 8W-31 (sheets 10 thru the end). It starts on page 735 of the 2307 page PDF file.

 

I know those diagrams are a pain to find, let alone read sometimes. I wish I still had access to dealerconnect.com but they finally cut my access since I don't work at the dealer anymore.

If you can find the diagram for the TCCM, concentrate on the 12v and ground. I think there are three grounds and one 12v wire, if I remember correctly.

I know that dealership diag can be 75-125 bucks an hour, but in cases like this its well worth it. Sadly, the PCM/TCM are the only modules that you can read with a standard OBDII reader, and if the code is anything other than a P0---, you won't get an accurate code description.

 

Guys, thanks. Yes, the TCCM has three grounds and what looks like one 12v lead from the power distr ctr. I printed out all diagram pages showing the TCCM on it. I'll check those to start. How would I rule out the TCCM? I'm guessing if the grounds and voltages check out, the TCCM is the likely culprit? What scenario would point to the CTM as faulty?

I'm wondering what the look on the dealer's face will be like if I took the truck in with the dash ripped out like it is now.

Here's a pic of my new ride btw...

 

I'm digging that plow!

Think about it like this like a radio. The radio has powers and grounds but it won't turn on unless it "knows" that the ignition key is in the run or acc position. A radio would have a wire that is 12v only when the key is in one of those two positions.

The TCCM on a Dakota, however, does not have a ignition switch feed. If you look at the diagram, there is no wire that is 12v when the key is on. It receives ignition switch information over the data bus. More specifically, it recieves that information directly from the CTM over the data bus.

If the circuitry for the bus fails in the CTM, the TCCM won't get that information, and the TCCM will not turn on. If that is the case on your truck, it would set a code in the TCCM like "missing ignition switch message".

I rush to fault the CTM because they are prone to cause a wide variety of failures. Thats especially true in 01+ Dakotas and Durangos. Also, I have diagnosed a problem exactly like yours and found the CTM to be bad. Of course because the error occurs over the data bus, there is no way to check it without a DRB.

 

Ok so, will the dealer be able to diag the problem even with the radio, heater and pass airbag harnesses disconnected?

 

Oh and btw, i may have to do the ball joints also. Front end sounds a bit noisy over bumps. I had the dealer run the VIN and they said the ball joint recall work was already done. So im guessin its the lowers that need replacing since the truck has only 50K miles on it.

 

Haha, I would probably reconnect any harnesses. In theory it shouldnt matter but they may give you a hard time about it. If you have gone to the trouble to remove the TCCM already I can imagine what the interior looks like haha

As for the ball joints, if they check them and the uppers are bad again, see if they will do the recall again. Those aren't a one time deal like most people think.