20 Most Recent 1989 GMC K1500 Questions & Answers


You need to retrieve transmissions faulty code with a scanner.
It looks like The PCM (powertrain control module) is in limping mode. It is the default mode when there is a faulty Transmission or engine code.

Hope it helps.

1989 GMC K1500 | Answered on Feb 18, 2019


have the fault codes read first using a scan tool with GM protocol installed ( not all scanners are capable of reading GM codes
there will be a code recorded
doubt if it will be a pump problem but it could be a pressure regulator problem or an EVAP system problem

1989 GMC K1500 | Answered on Jul 14, 2017


Have you chg. fuel filter? If so, best to do a fuel pressure test, sometimes( not always) when the pump gets warmed up they can loose a little pressure and thats all it takes just a few # under recamended p.s.i and the truck quits running, you may hear the pump run but its not putting out the correct pressure until it cools down and it starts working again, but after a while quit all together.

1989 GMC K1500 | Answered on Jan 19, 2016


Check the coil, the control modual in the distributer, and the ecm. thats what controls the injectors.

1989 GMC K1500 | Answered on May 05, 2015


crawl under truck and on front diff unhook actuator put fuse in if your fuse doesn't blow id say actuator is bad my plow truck did same thing and I think my blower motor stopped too

1989 GMC K1500 | Answered on Feb 17, 2015


You could have weak engine control module or a pick-up coil. Have your module tested first.

1989 GMC K1500 | Answered on Jan 19, 2015


You might have somebody press the pedal as you get down and check the clutch travel. Might have an adjustment on the clutch arm.
Could have wrong pressure plate, did you match them. I would check the travel first.

1989 GMC K1500 | Answered on Jan 19, 2015


Check to see if you have power going to the switch with a test light. Also do the turn signal lights light up on the dash as you lift the arm up or push it down. If so you have a bad flasher which will located under the dash towards the firewall.

1989 GMC K1500 | Answered on Jan 19, 2015


I had a same problem on a Chevy. and it turned out to be vacuum I had to rebuilt the heads. As I drove it would run rough, as soon as I would check it out I would not find any vacuum.

1989 GMC K1500 | Answered on Jan 19, 2015


Sounds like your pump is having problems pumping fluid due to a plugged up transmission filter. Or it might be going bad.

1989 GMC K1500 | Answered on Jan 19, 2015


Spark plugs are set at 0.035 inch.
Ignition timing is set at 0 degrees BTDC. The computer then controls the timing from there. There will be a wire that you unplug before you set the timing, then once you have verified that the timing is at 0 degrees, then reconnect the wire and you're done.

1989 GMC K1500 | Answered on Jun 01, 2014


get a haynes repair manuel, worth every penny, just do it

1989 GMC K1500 | Answered on Apr 27, 2014


check to make sure you have no vacuum leaks. u can use a cheap can of carburator cleaner and spray around the vacuum lines of the truck, if your truck starts idling up and changing, you have a leak then just replace the line. Older GM vehicles rely on Vacuum advances for the transmission and will not shift properly nor downshift if there is a leak. a lot of vehicles rely on vacuum to support many functions, mainly driveability as well as smooth running. there should be a vacuum line that runs near the rear of the transmission. also might want to check transmission fluid for the no power, cause even though you may have power in 1st and 2nd, 3rd gear is your main drive gear unless you have a 700R4 with automatic overdrive and it could be suffering from not enough fluid getting to the bands from the pump. also one more thing, check the downshift linkage cable the runs from the carburator to the transmission, make sure it is working, sometimes you can have a broken cable in the line and not even know it. hope this helps

1989 GMC K1500 | Answered on Apr 07, 2014


what have you checked so far ? will it start using starting fluid sprayed into the intake ?

1989 GMC K1500 | Answered on Jan 23, 2014


Should be fairly easy. You disconnect the battery, release tension on the belt, and remove the alternator.

1989 GMC K1500 | Answered on Jan 17, 2014

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