Service Engine Codes??

I have a 95 Silhouette and the service light is coming on. I took it to Advance auto and they read the codes for me.

Paper says:

History Code P0321
Ign System Problem
18X Interrupts Lost Signal

History Code P0361
Ign System Problem
Elec Spark Timing
EST Not Toggling

What could be the problem??

Thanks

We prefer that you post model specific problems at the right subforum where you may get a better and/or faster response.

Thread moved to Olds Silo.

The missing 18X signal indicates a possible flaky crank position sensor or problem with the ICM module.

I have the post in the Silhouette part of the forums. Noone looked at it.

Thanks though

I have the post in the Silhouette part of the forums. Noone looked at it.

Thanks though

It probably would have been the same at Olds Non-Specific.

Basically your problem is an ignition circuit problem. The crank position sensor generates the 18X timing pulses. On the P0361 DTC, the PCM has detected either a short or open in the bypass or IC circuits. It is not toggling between the 2 modes. The PCM will switch between IC and bypass mode. This establishes the initial timing and spark advance.

The possibilities are the crank sensor, the Ignition Control Module (ICM) or wiring either at the crank sensor, ICM module and/or the PCM module. To check the wiring you will most likely need a GM wiring diagram and a multimeter.