SES/Temp Light, Speedometer to 0, Engine Stalls PROBLEM FIXED!
rbinms33
12-02-2004, 06:57 PM
Just wanted to pass on my '90 Olds 98 3.8L engine stall problem and what finally fixed it.
Symptoms: SES light and Temp light flickers and the speedometer goes to 0 with accompanying loss of power like the engine is going dead. Doesn't matter if it's hot or cold, morning or night, rainy or sunshine. Doesn't do it all the time, sometimes very intermittent, other times I wondered if I would make it home it was doing it so bad. Towards the end, sometimes just the speedometer would go to 0 with an SES light and the car would run fine.
Troubleshooting: Since I had access to a test gauge, I checked fuel pressure first and it was within the Chilton's specs. Later when the speedometer went to 0 with an associated SES light but the engine ran fine, I figured it wasn't the fuel system. Although I did go buy a Chilton's manual to get an idea of what I was up against, be warned, when it comes to the wiring diagrams, these manuals are lacking.
Next, I checked the trouble codes on the OBDC but it only flashed 12 at me. Funny thing is, I did get it to spit out some codes one night. One of those nights when I didn't think it would get me home and it flashed 5 different fault codes at me. When it did give me the codes it would flash 12 three times and then each of the codes three times. Started suspecting the ECM but wanted to finish troubleshooting first.
I found out through my Chilton's manual that the speedometer goes through the ICM. Inspected the ICM and it had some kind of yellow goo running out of it. Replaced ICM, plugs (must have been original cause they were gapped at .080) and wires but no help.
Finally broke down and got a subscription to Alldata and got the wiring diagrams I needed. Ruled out Coolant Temp Sensor (1.6 K ohms cold and 280 ohms hot) and Vehicle Speed Sensor (constant AC voltage when vehicle moving and problem duplicated). Driving down the road, the ECM was receiving power and had good ground when problem was duplicated. Bit the bullet, replaced the ECM with one from O'Reilly's and lo and behold, everything is fine now. If you do replace your ECM, remember to remove the module under the cover of the old ECM and install it in the new one.
I hope this helps anyone encountering the same problem. I know it's frustrating but this car only has 103K miles on it and has been too good to me to let some electrical problem get the best of me.
Symptoms: SES light and Temp light flickers and the speedometer goes to 0 with accompanying loss of power like the engine is going dead. Doesn't matter if it's hot or cold, morning or night, rainy or sunshine. Doesn't do it all the time, sometimes very intermittent, other times I wondered if I would make it home it was doing it so bad. Towards the end, sometimes just the speedometer would go to 0 with an SES light and the car would run fine.
Troubleshooting: Since I had access to a test gauge, I checked fuel pressure first and it was within the Chilton's specs. Later when the speedometer went to 0 with an associated SES light but the engine ran fine, I figured it wasn't the fuel system. Although I did go buy a Chilton's manual to get an idea of what I was up against, be warned, when it comes to the wiring diagrams, these manuals are lacking.
Next, I checked the trouble codes on the OBDC but it only flashed 12 at me. Funny thing is, I did get it to spit out some codes one night. One of those nights when I didn't think it would get me home and it flashed 5 different fault codes at me. When it did give me the codes it would flash 12 three times and then each of the codes three times. Started suspecting the ECM but wanted to finish troubleshooting first.
I found out through my Chilton's manual that the speedometer goes through the ICM. Inspected the ICM and it had some kind of yellow goo running out of it. Replaced ICM, plugs (must have been original cause they were gapped at .080) and wires but no help.
Finally broke down and got a subscription to Alldata and got the wiring diagrams I needed. Ruled out Coolant Temp Sensor (1.6 K ohms cold and 280 ohms hot) and Vehicle Speed Sensor (constant AC voltage when vehicle moving and problem duplicated). Driving down the road, the ECM was receiving power and had good ground when problem was duplicated. Bit the bullet, replaced the ECM with one from O'Reilly's and lo and behold, everything is fine now. If you do replace your ECM, remember to remove the module under the cover of the old ECM and install it in the new one.
I hope this helps anyone encountering the same problem. I know it's frustrating but this car only has 103K miles on it and has been too good to me to let some electrical problem get the best of me.
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