92 Bonneville Check Engine Light comes on randomly
 

My 92 Bonneville check engine light just start coming on and off randomly. When this happens the cruise control will cut off and not work until the light goes out and the transmission will shift down out of overdrive. To get an error code will the check engine light need to stay on to read the code? Has anybody seen this type of problem? Also one time this happen I lost throttle control until the light went out.

Reggie

You should be able to retrieve the code even if the light is off. Post it up and we will get you on the right track.

I will take it to Auto Zone to have them read it.
Thanks

You don't need to take it to Autozone. Got paperclip? You can do it yourself.

Jump pins A and B, turn power on, and count the flashes. The first code will always be 12. This says the OBD system is OK.
For example...code 12.
Flash, pause, flash, flash.
If there are other codes, you will have a longer pause between the codes, for example. code 12, and code 15
flash, pause, flash, flash, pause, pause, flash, pause, flash, flash, flash, flash, flash.

Then, I think it will repeat.

https://www.gmforum.com/attachment.p...ine=1331672758

Thanks Mike1995 for that information. I will give that a try and poet the code that I get.
Reggie

Mike1995,
What will flash?

Reggie

Oh, sorry, your check engine light will flash.

Did what mike1995 suggested and it came back with this 21. Look up the code and it is the Throttle position Sensor Circuit (Signal Voltage High) I'm guessing the Throttle Position Sensor is bad?
Reggie

For some reason the PCM is seeing the voltage higher then expected coming back from the TPS. Normally, the PCM sends 5 volts to the sensor, when you press on the gas, the PCM sees the voltage coming back at different values as you change throttle.

You could swap it out with a new one.

https://www.gmforum.com/trouble-shooting-test-procedures-141/throttle-position-sensor-tps-signal-voltage-284385/
https://www.gmforum.com/trouble-shooting-test-procedures-141/throttle-position-sensor-tps-plug-test-284306/
https://www.gmforum.com/trouble-shooting-test-procedures-141/testing-tps-throttle-position-sensor-279319/

you can test the tps, open circuits cause high voltage so look for broke or loose wires bad connections

I check the voltage on the TPS connector and is was at 5V. The resistance on the TPS varied from about 1.2k to 5K uniformly. Drove the car for about 15 minuites to get it hot (No check Engine light) and recheck the Voltage and resistance. Resistance the same. On the voltage I'm not sure if this was just a glitch when I connected the voltage but it show I thank @9V but my ground fallout and when I connected it back up the read was back to 5V. What does everybody think?

not sure how you could get 9v on a 5v circuit.

I'm thinking that maybe the ground was not connected good and what I seen was maybe 9xx mv and not 9v. I just saw it for a split second before the multimeter ground probe fell off the connector. The connectors plastic is real brittle. Is this normal? Should I try to replace the connector it?

to me that would seem like the next step.

I replaced the connector and it did not help. I'm guessing the next step is to replace the Throttle position sensor. Is there anything else that I need to check first before I replace the sensor?
reggie