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Dan
Dan, Technician
Category: Jeep
Satisfied Customers: 24465
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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My check light came on and I got a P1698 code, Engine check,

Customer Question

My check light came on and I got a P1698 code
JA: Just to clarify, what are the exact lights you're talking about?
Customer: Engine check
JA: What is the model/year of your Jeep?
Customer: 04 Grnd Overland
JA: What year is your Jeep?
Customer: 04
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yeah.... plus sometimes it dead and won't start
JA: Anything else you think the mechanic should know?
Customer: When it won't start it's a no crank with good battery
Submitted: 1 year ago.
Category: Jeep
Expert:  Dan replied 1 year ago.

Hello, my name is***** engine do you have? Thanks.

Customer: replied 1 year ago.
4.7 H/O
Customer: replied 1 year ago.
Would it be easier to continue by phone?
Expert:  Dan replied 1 year ago.

I am fine doing this over chat which will be cheaper for you too.

Customer: replied 1 year ago.
Great LOL.... cheaper is better
Expert:  Dan replied 1 year ago.

This code sets when the PCM determined that it did not receive any Transmission bus messages over the Data Bus line for 20 seconds. When it sets it usually means the transmission control module has failed. During problem Check for power to the TCM on pins 11 and 56. Check for good ground on pins 37, 39, 53, and 57. Verify no voltage (less than 100 mV) on pin 8. If all OK, replace the TCM. Here is a picture to help locate, let me know if you have more questions. Thanks.

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https://www.dropbox.com/s/qe2eik405zg6k6y/tcm1.pdf?dl=0

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https://www.dropbox.com/s/5yghq3sakiqb1ee/tcm2.pdf?dl=0

Customer: replied 1 year ago.
Would the TCM cause a no crank?
Expert:  Dan replied 1 year ago.

Yes because the transmission range switch which tells vehicle you are in park/neutral goes through transmission control module. Let me know if you have more questions, thanks.

Customer: replied 1 year ago.
You have helped a lot.... not used to civilian vehicles but I know what the TCM does as I worked on HMMWVs in the army but they don't prevent a no crank on the those army truck.
Expert:  Dan replied 1 year ago.

I'm happy to help, let me know how it turns out or if you run into more questions. You can reply to this answer at any time without additional fees. Thanks!

Customer: replied 1 year ago.
Thanks a lot Dan!
Expert:  Dan replied 1 year ago.

No problem, make sure to keep me updated. Have a good evening!

Customer: replied 1 year ago.
Do I just bookmark this page to be able to get back with you?
Expert:  Dan replied 1 year ago.

Correct, then just reply like you are now.

Customer: replied 1 year ago.
Great... I appreciate everything and you have a good evening as well.
Expert:  Dan replied 1 year ago.

Thanks, I'll talk to you later.

Customer: replied 1 year ago.
Having an issue with the correct rotation of the TCM connector.
Customer: replied 1 year ago.
Or orientation might be the proper term.
Expert:  Dan replied 1 year ago.

Best way to figure it out is look at pin numbers/colors on diagram and see what connector matches. Pin 1 is light green/black and pin 2 is tan black, pin 3 is violet, and pin 4 is empty.

Customer: replied 1 year ago.
Ignition position where during power test?
Expert:  Dan replied 1 year ago.

Key should be in on position.

Customer: replied 1 year ago.
Okay.... seems to point to TCM! Battery voltage at 11 and 56.... continuity on all ground pins!
Expert:  Dan replied 1 year ago.

Also verify no voltage on pin 8, if all are good then I agree TCM needs to be replaced. Let me know how it goes, thanks.

Customer: replied 1 year ago.
Battery voltage on pin 8 with ignition on :)
Customer: replied 1 year ago.
That was supposed to be a :(
Expert:  Dan replied 1 year ago.

I meant to say it should have voltage, so it looks like everything is testing out OK leaving TCM as cause. Let me know how it goes, thanks.

Customer: replied 1 year ago.
Okay... if all checks out you are the man!
Expert:  Dan replied 1 year ago.

Let me know how things go when you get a chance to replace. There is still a possibility the problem is PCM but unlikely and there is no way check more then we have. This code is usually caused by TCM though. Keep me updated. Thanks.

Customer: replied 1 year ago.
Will do and I hope this fixes the problem.
Expert:  Dan replied 1 year ago.

I think it will, I'll talk to you later. Thanks.