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Dan
Dan, Technician
Category: Jeep
Satisfied Customers: 23590
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: 4 months ago.
Category: Jeep
Expert:  Dan replied 4 months ago.

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

Customer: replied 4 months ago.
4.7 H/O
Customer: replied 4 months ago.
Would it be easier to continue by phone?
Expert:  Dan replied 4 months ago.

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

Customer: replied 4 months ago.
Great LOL.... cheaper is better
Expert:  Dan replied 4 months 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 4 months ago.
Would the TCM cause a no crank?
Expert:  Dan replied 4 months 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 4 months 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 4 months 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 4 months ago.
Thanks a lot Dan!
Expert:  Dan replied 4 months ago.

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

Customer: replied 4 months ago.
Do I just bookmark this page to be able to get back with you?
Expert:  Dan replied 4 months ago.

Correct, then just reply like you are now.

Customer: replied 4 months ago.
Great... I appreciate everything and you have a good evening as well.
Expert:  Dan replied 4 months ago.

Thanks, I'll talk to you later.

Customer: replied 4 months ago.
Having an issue with the correct rotation of the TCM connector.
Customer: replied 4 months ago.
Or orientation might be the proper term.
Expert:  Dan replied 4 months 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 4 months ago.
Ignition position where during power test?
Expert:  Dan replied 4 months ago.

Key should be in on position.

Customer: replied 4 months ago.
Okay.... seems to point to TCM! Battery voltage at 11 and 56.... continuity on all ground pins!
Expert:  Dan replied 4 months 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 4 months ago.
Battery voltage on pin 8 with ignition on :)
Customer: replied 4 months ago.
That was supposed to be a :(
Expert:  Dan replied 4 months 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 4 months ago.
Okay... if all checks out you are the man!
Expert:  Dan replied 4 months 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 4 months ago.
Will do and I hope this fixes the problem.
Expert:  Dan replied 4 months ago.

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

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