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88 GMC S15 won't shift into OD


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mrswassam
New User

Oct 2, 2013, 6:56 AM

Post #1 of 7 (1880 views)
88 GMC S15 won't shift into OD Sign In

1988 GMC S15 4.3 4X4 Pickup - 109000 miles - will not shift into over drive. It seems to shift into lower gears at high rpms but after a couple miles at high speed it will not shift into OD and check engine light comes on.
Fulids all looks good.
Changed TPS and nothing changed.

Thanks!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 2, 2013, 6:57 AM

Post #2 of 7 (1879 views)
Re: 88 GMC S15 won't shift into OD Sign In

So, what is the code being set when the check engine light comes on?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



mrswassam
New User

Oct 2, 2013, 7:00 AM

Post #3 of 7 (1875 views)
Re: 88 GMC S15 won't shift into OD Sign In

That I don't know.
Local autoparts store can't read code on a model that old.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 2, 2013, 7:04 AM

Post #4 of 7 (1870 views)
Re: 88 GMC S15 won't shift into OD Sign In

Of course not. It's OBD1. That doesn't mean it can't be done.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



mrswassam
New User

Oct 2, 2013, 7:07 AM

Post #5 of 7 (1867 views)
Re: 88 GMC S15 won't shift into OD Sign In

Okay - thanks.
If I can find somebody who can get the code for me I'll know what to start looking at.
Here I was looking for suggestions to start troubleshooting without the code reader.
Thanks anyway!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 2, 2013, 7:35 AM

Post #6 of 7 (1855 views)
Re: 88 GMC S15 won't shift into OD Sign In

You can try it this way but it's pretty easy to read them wrong.



To extract a trouble from the computer for diagnostic purposes, the Assembly Line Communication Link (ALDL) connector is used.
Ground terminals A and B with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. A 12 consists of one flash, a short pause, then two flashes in rapid succession.
After 12 is displayed, any stored trouble s will be displayed by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" light. All s are displayed 3 times each then a 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.




ALDL Connector (Located Underdash)


The ALDL diagnostic connector is located in the passenger compartment.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Oct 2, 2013, 7:40 AM

Post #7 of 7 (1851 views)
Re: 88 GMC S15 won't shift into OD Sign In

Jumper A to B with a paperclip.





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