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Brad, Jeep Dealership Tech
Category: Jeep
Satisfied Customers: 7622
Experience:  19 Yrs Chrysler/Dodge/Jeep. ASE Master (L-1) Certified
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Jeep Grand Cherokee Laredo: I have a 2007 Jeep grand cherokee

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I have a 2007 Jeep grand cherokee WH 3 ltr crd.
It goes into limb mode, and warnings: "Transmission over temp" "Service 4WD" ESP/BAS, ETC.
Codes recovered:u1408 brake signal
P0672 Glow plug circuit X 2
C107C Brake pedal switch
B1668 rev lamp circuit high...fix =take aftermarket LED out and put original back in.
C140A Transfer case motor performance
u0415 impausible data received from ABS
P0605 control unit faulty.
I had my battery tested and was bad, it has been replaced.

So if I replace the tail lights etc small jobs, should I also order and replace the glow plugs and the transmission motor or just do lights clear the codes and see what happens.
As I will import the parts from the USA to Australia I will have a two week wait between ordering and recieving parts which could take ages to resolve the problems.

How would you suggest I approach this?

Brad :

Hello welcome to JustAnswer, My name is XXXXX XXXXX I will be assisting you.

I see your question has been up for several hours,
Do you still need any assistance?


JACUSTOMER-vmz9dw2x- :

thanks Brad, I think I will ask more specific stuff once I get more into it.

Customer: replied 4 years ago.
Further to the scanner picking up code C140A and then with reference to the service manual testing 21-929,
Test 2 passes no voltage T315 circuit
Test 3 passes no voltage T316 circuit
Test 4 passes no short to ground circuit T315
Test 5 passes no short to ground circuit T316
Test 6 FAILS short on transfer motor pins on circuits T315 / T316.

Anything else I should test here pull the transfer motor out and see if locally repairable Australia? I tried that on CV joints and got charged 80% more than Rock Auto USATESTING TRANSFER MTR even including freight . Rock Auto remanufactured $180.00 inc freight exUSA
Can you fault my diagnostics or logic?
Now off to test those temp / solinoid sensors in the diffs for the "trans over temp warn" Then we have the open circuit on glow plugs to deal with.

Hi Tony,

Great job at documenting the testing process and you are correct.. I don't think it can be repaired, most parts now-a-days are cheaper to replace than to rebuild..

Post the results of the Temp/Solenoid, and Glow-Plug tests if you need anymore assistance

Brad and 5 other Jeep Specialists are ready to help you
Customer: replied 4 years ago.

Hi Brad

Attached is the dignostic report I had done by a auto transmission specialist.

Temp Light coming on I get "Transmission over temp" and "serviceXXXXX

The service manual tells be to look at 21-443,:sensor transmission temp which is part of the TRS which appears quite complex, whats your thoughts?

The reason why I am leaning towards diffs as they have a temp sensor too and last month I changed the diff mounts and dropped the front diff 6-10 inches with the wires still connected of course they were forced to disconnect after that, they looked good but....? warrant some testing now?

Other codes that are fixed B1668 we put led in ..taken out and originals in.

Codes: u1408 c107c these items work fine.


The glow plugs, Australia is a hot country our temp hardly ever gets below 40f. Do we need them can I disarm that circuit?


I think I only have the codes U0415 and overtemp + service transmission left, what do you reccommend I look at next with the service manual ref numbers?

Hi Tony,

May I have the last 8 of you VIN to correctly look up your vehicle?

Customer: replied 4 years ago.

Hi Brad,

Vin no: 6Y165276.

Also I have brought two scanners

I returned this one and replaced with:

Neither scanners can read any codes except for:

U0101 Lost communication with TCM.

The supplier of the ms609 is suggesting the TCM is bad and has suggested trying to clear the above code and disconnecting the battery to see if that takes the car out of limb mode.


Below is scan reports from a Auto Electrician that I had done when I replaced the battery last week.

Hi Tony,

Is the TCM is only communication code you have? If so here is the communication wiring to verify that it's not shorted anywhere.

Customer: replied 4 years ago.

Hi Brad, I am stuggling with just a wiring digram without more info where to test, I did find in the junction box fuse F3 10 amp has no power to it.

With my scanner I only get one code "lost communication with TCM" I have the 2005 /08 WK service manuals and wanted to carry out tests 8E-236, but cannot find the TCM to unplug TCM C1 Harness!

The company that supplied the ms601 scann tool has came back and said bad TCM or associated wiring.

Trust this is not frustrating you?




Hi Tony,

The TCM is under the steering wheel here:

you will need to look above the steering column and find the cutout in cover... it is under the insulation...
Customer: replied 4 years ago.
I do not think that is right for right hand drive models
Customer: replied 4 years ago.

from the test above on the transfer box motor, if the TCM detects this faulty will the TCM shut down all communication and put the jeep into permenant limp mode untill those codes C140A are cleared which in turn making the U0101 error false.


Solution / logic?

Under these fault conditions my scanner wont get to the TCM to clear the C140A code because the TCM has shut down communication.

Whats the opinion on, as I have fixed some codes with brake lights etc, just concentrate on the transfer case motor which is sugesting a short which I should be able to pull apart and confirm fix as nessary then back to the mechanic that can clear these codes or the dealer just for a starscan and report and clearing of codes.

Hi Tony,

I think you are a bit confused. The U0101 is dealing with the TCM.. And the C140A is dealing with the FDCM(Front Drive Control Module). THe C140A is TransferCase Motor Performance.. Here is the info:

For a complete wiring diagram, refer to the Wiring Information

  1. When Monitored:

    With the ignition on and no undervoltage or overvoltage condition present.

  2. Set Condition:

    A faulted condition is detected in the H-bridge driver.

Possible Causes


The TCM will not clear this code.. Will your scantool communicate with the FDCM?

Also if you erase all the codes, which ones come back as active?

Customer: replied 4 years ago.

I have installed the remanufactured from the USA transfer case motor, I have not touched any wiring just plugged it in.

I also have my own scanner now that works from the USA as well Autoenginuity enhanced Chrysler package.

I have these codes:

FCM and ABS U0101

Enhanced power train, U0101,P0676, P0672, P0671

TCM, P0605

When I try clear codes the vechile refuses to clear them.

Other warnings on the dash


'serviceXXXXX "Transmission over Temp" ETC flashing when engine is on / off. ESP/BAS light on all the time.


The car is in Limp mode.

I have found the TCM, behind the radio I think Jeep changes things for the RHD cars and its not altered in the service manuals.

What do you suggest?

Let me look up these codes...
Customer: replied 4 years ago.
OBD-II Diagnostic Trouble Code Report

Shop: Home
Address: 238 Dulong rd
Phone: 0754761692 Fax: 0754761692
Email: [email protected]
Timestamp: 25/07/2012 02:39:02

Make: Jeep Model: Grand Cherokee Year: 2006

MIL: Off


Diagnostic Trouble Codes

Generic Powertrain

U0101 Lost Communication with TCM


Enhanced Powertrain

P0676 Cylinder 6 Glow Plug Circuit

P0672 Cylinder 2 Glow Plug Circuit

P0671 Cylinder 1 Glow Plug Circuit

U0101 Lost Communication with TCM


Anti-Lock Brake System

U0101 Lost Communication with TCM


Audio Amplifier

No response from module


Auto Highbeam Module

No response from module


Cabin Compartment Node

No diagnostic codes retrieved


Climate Control

No response from module


Driver Door Module

No diagnostic codes retrieved


Electronic Overhead Module

No diagnostic codes retrieved


Front Control Module

U0101 Lost Communication with TCM


Hands Free Module

No response from module


Heated Seat Module

No response from module


Intrusion Transceiver Module

No diagnostic codes retrieved


Light/Rain Sensor Module

No response from module


Master Audio Unit - Radio

No diagnostic codes retrieved


Memory Seat Module

No response from module


Occupant Classification Module

No response from module


Occupant Restraint Controller

No diagnostic codes retrieved


Parktronics Module

No response from module


Passenger Door Module

No diagnostic codes retrieved


Satellite Radio

No response from module


Steering Column Module

No diagnostic codes retrieved


Sunroof Module

No response from module


Transmission Control Module

P0605 Internal Control Module Read Only Memory (ROM) Error

U0121 Lost Communication With Anti-Lock Brake System (ABS) Control Module

U0100 Lost Communication With ECM / PCM A

U0164 Lost Communication With HVAC Control Module

U0114 Lost Communication with Four-Wheel Drive Clutch Control Module

U110b Lost Engine Coolant Message

U0103 Lost Communication With Gear Shift Module

U0155 Lost Communication With Instrument Panel Cluster (IPC) Control Module


Vehicle Entertainment System

No response from module


Wireless Control Module

No diagnostic codes retrieved

I have confirmed there is 12v and a ground on the TCM.

Your recomendation next?

Hi Tony,

Thank you for the info.. I have read them and you have a BUS issue.. The BUS is the 2 wires that all of the modules use to communicate with each other.. Here is how to fix it.. Get your multi-meter and in your DLC under dash measure the voltage of pins 6 and 14. The voltage should be at 2.5v. If it's not you need to ohm each one to ground, if either one ohm to ground a wire is shorted somewhere.. If neither ohms to ground it's a module locking the bus down.. Keep meter in DLC and start unplugging each module until the voltage returns to 2.5v..





1 - -
2 - -
3 - -
8 - -
9 - -
10 - -
11 - -
12 - -
13 - -
15 - -
16 A108 20LG/RD FUSED B(+)
Customer: replied 4 years ago.

Hi Brad

The voltage to pins 6 and 14 is 2.4 to 2.45 volts. Resistance to earth is one indicating no short to earth. Battery voltage 11.5 but its a new battery and I suspect is a little flat because of the testing leaving the key.

Hi Tony,

-If you erase all of the codes in the system.. What are the hard active codes that reappear? I would like to know what is happening right now.. Because from the look at your previous code list, it looks like most of the modules are down..

Customer: replied 4 years ago.
Customer: replied 4 years ago.

Hi Brad

The procedure I followed, scan enhanced powertrain and show all codes.

Delete all codes.

Scan all enhanced power traincodes, save scan results attached above.

Also confirmed DLC pins 6 and 14 still 2.4 volts and no circuit to earth all still good.

Confirmed voltmeter reading accurate against my travel trailer solar charger....voltmeter confirmed good.

Should I put a 20 watt test lamp across pins 6 and 14 to confirm voltage under some load?


Hi Tony,

-Again thank you so much for providing me with such great info!!!!!!

If you will take a look at your 2nd pic, I see a P-0605 Internal Controller ROM failure.. I went and pulled up diagnostics and there is none, it says replace the TCM.. So I would 100% replace the TCM based on that code.. Usually when I get a internal controller failure something is wrong with the circuitboard of that controller.. The P0601 is common for a PCM failure...

And by my data it is here:
1. Locate the transmission control module on the dash panel, under the dash panel silencer pad (2), just to the right of the steering column.
2. Locate the cut lines (1) marked on the silencer pad. Cut the pad along these lines.

If you have located it at a different spot since it's a RHD vehicle, then that is good.. Just make sure that it is the TCM.. After you replace it, post back the results..

And the 3 Glow-Plug codes, do you have them unplugged or is that another issue?

Customer: replied 4 years ago.

The glow plugs are plugged in untouched, a supplier in Europe has suggested I take one out and send him the part number, $12.00 ea there $80ea in Australia! I dont think they are the problem but it will remove three codes!


Found the TCM attached is a photo, last night I tried two autocomputer remanufactures in the USA with one cant do and one no responce, could be because its a MB Seimens / european part?.


Do you have any suggested suppliers? I imagine the dealer here will be arount $2000.00.

Customer: replied 4 years ago.
I have found a Australian computer company to test and repair. so will see how it goes
Hi Tony,

-That is it!!!!! Great job!

I can't read the part number but when I look up your vehicle with VIN number, I get a(NNN) NNN-NNNNG but it changes to a RL692392AI part number and price is 512.00.

Here is the wiring for the injectors:

If the wires are good going to the injectors, the issue is either the injectors or the Glow Plug Module..

I have no suppliers I can suggest other than US Suppliers.. I would do a search for either part number in your area to see what comes of that..

Customer: replied 4 years ago.

Hi Brad,

The TCM cannot be repaired or even tested in Australia.

The Jeep dealer has no stock in Australia they have to import, they came up with the same part number as you. But in the photo above it has a different part number. Guess we use the part number you and the jeep dealer specified?


A TCM supplier in the USA is offering a rebuilt one with life time warranty plug and play programmed with my vin and milage for $500.00 includes a $150.00 core charge.

If I buy new it will not be plug and play?

I will need to go to the jeep dealer and get them to programme, should I ask them to give a estimate to programme it in the car and maybe a starscan after? They wanted $900.00 to import a TCM for me.


Whats your advise new or rebuilt considering the above?


I am replacing all the glow plugs, What a tricky job! You guys must be a mixture of Dentists / Surgeons extracting those!

Hi Tony,

-Sorry for the delay.. We are a few hrs apart.. If you were to get the TCM it is plug and play, no programming needed.. No quicklearn or anything.. You have a NAG1 trans and it will learn everything it needs..

If you get a rebuilt one with warranty, I don't see why not to go that route..

Customer: replied 4 years ago.

Hi Brad,

Got the TCM today part number RL692392-AI they said superceded our part numbers.

Pluged it in scan...deleted all codes....scan again...have not started motor.

Glow plug issue gone.

Two errors

1/ occupant restraint controller: B210D low voltage , note battery voltage 12.4

2/ TCM: P1644 incorrect config.


I have not started the motor as yet.

Your next suggested procedure?




7th Aug 2012

Hi Brad latest report attached / below


Customer: replied 4 years ago.

Hi Brad,

Plugged in the new TCM part number RL692392AI.

Ran a scan and then cleared all codes.

Ran the scan again and got two errors. Glow plug issue gone. Other dash board warnings have gone as well. I have not started the motor as yet, in a couple hours I will.



Started it no fault codes on dash, engine cooling fans returned to normal. Park to rev OK, rev to drive ok, stays in 2nd or 3rd gear after driving 300 yards up to 50mph. Turn around come home same. no dashboard warnings on.

Run scan below are results New codes MIL and P0700 previous still on B210D P1644, A hour later I cleared the codes took it for a very small drive and the same codes came back.




Update: Brad, I took it to the dealer in programme the TCM and other computers in the car.....All fixed Runs Great!






Customer: replied 4 years ago.

Hi Brad,

All fixed now, the Dealer programmed the new TCM at a small cost.

It runs great.


Customer: replied 4 years ago.
Entirely wrong