I have a 95 Lesabre with the check engine light on. The diagnostic code I got is 1640 after trying several scanners to find one that would read obd 1.5. The guy who scanned it told me the code was for the ecm. Another symptom is that (in park). the car will rev to about 4000 RPM then go back down to 3000. It won"t rev past 4000. My instinct is to get an ecm from the junkyard and slap it in. But first I want to see if anyone has had this experience or has any suggestions.

There is a rev limiter at 4000 RPM if the car is going less than 15 MPH. That part is normal.

However, on most OBD 1.5 (like yours), P1640 seems to indicate that Quad Driver Module 1 is on the fritz. Here'* one thread about it; you can search for "P1640" and find many more.

Thanks. It"* my understanding that I can"t buy a QDM1. So what is the actual part that I have to buy?

https://www.gmforum.com/showthread.p...ighlight=p1640