86' GMC Jimmy 2.8l
Question:
Howdy, I’ve had an 86 GMC Jimmy with the 2.8l V6 and 4 wheel drive since 98 (got it with 60k on it). Right now it has about 135k. My alternator just threw out a bearing and was making a horrible whining sound so I dropped the money and bought a brand new one and put it on myself. The alternator is charging, steady voltage and appears to be working properly. But after I put the alternator I got a new problem and that is stalling, it was random at first till I kinda figured out what would make it cause. Opening the engine up and then slowing down quickly while turning is instant stall. Sometimes while driving at highway speed and needing to hit the brake for a turn the seatbelt light will blink and beep and the engine will sputter and go. And then finally the service engine light would start flashing when this happened. So at this point that gave me a place to start … I read error codes 12, 21, and 24. 12 = normal – diag. 21 = TPS (Throttle position sensor) 24 = VSS (vehicle speed sensor) Alright.. 21 .. woo hoo .. i’m familar with this one as i’ve had it 3 times in the 3 years i’ve owned this car. Replacing the TPS would fix it … for a year. All 3 times the symptoms were different. And the 4th time is definately a different symptom, IF it’s the tps. From my understanding there isn’t really much you can do with a VSS, as long as your speedo is working the VSS is working, correct? My question is , would replacing the TPS be a waste of money and not solve the issue as I probably have something more serious? I’d like to take care of this tomorrow as it’s a day off, so any replies would be greatly appreciated, specially if you have seen this issue and you have a fix. Any help is welcomed and most appreciated… thank you. Corny
Response:
Your code descriptions aren’t quite right (or at least incomplete:) 21 TPS voltage was above 2.5 volts for 5 seconds when the MAP sensor signal showed manifold vacuum above 15 pounds or TPS signal voltage was over 4.5 volts. 24 When engine speed was between 1400 and 3600 RPM and throttle angle was less than 2%, the MAP sensor signal showed low voltage (High manifold vacuum) for at least 3 seconds. Clearly these codes are inter-related. The problem is an inconsistency between the signals from the TPS and MAP sensors. Since you say you replaced the TPS already, I’d take a good look at the MAP sensor.. — Robert Hancock Saskatoon, SK, Canada Home Page: http://roberthancock.netfirms.com/
– Hide quoted text — Show quoted text -> Howdy, > I’ve had an 86 GMC Jimmy with the 2.8l V6 and 4 wheel drive since 98 (got it > with 60k on it). Right now it has about 135k. > My alternator just threw out a bearing and was making a horrible whining > sound so I dropped the money and bought a brand new one and put it on > myself. The alternator is charging, steady voltage and appears to be > working properly. > But after I put the alternator I got a new problem and that is stalling, it > was random at first till I kinda figured out what would make it cause. > Opening the engine up and then slowing down quickly while turning is instant > stall. Sometimes while driving at highway speed and needing to hit the > brake for a turn the seatbelt light will blink and beep and the engine will > sputter and go. > And then finally the service engine light would start flashing when this > happened. So at this point that gave me a place to start … I read error > codes 12, 21, and 24. > 12 = normal – diag. > 21 = TPS (Throttle position sensor) > 24 = VSS (vehicle speed sensor) > Alright.. 21 .. woo hoo .. i’m familar with this one as i’ve had it 3 times > in the 3 years i’ve owned this car. Replacing the TPS would fix it … for > a year. All 3 times the symptoms were different. And the 4th time is > definately a different symptom, IF it’s the tps. From my understanding > there isn’t really much you can do with a VSS, as long as your speedo is > working the VSS is working, correct? > My question is , would replacing the TPS be a waste of money and not solve > the issue as I probably have something more serious? > I’d like to take care of this tomorrow as it’s a day off, so any replies > would be greatly appreciated, specially if you have seen this issue and you > have a fix. > Any help is welcomed and most appreciated… thank you. > Corny
