Okay where is this EST circuits. Is it in the opti, anything related to the opti?


41 Ignition Control (IC) circuit (open circuit)

42 Ignition Control (IC) circuit (shorted or grounded circuit)

Where is this control? The ICM I suspect. Any test or anything I can do? I am just looking for some steps to diagnose and find why I am getting these codes.

And also when I was trying to figure out why the engine was surging and high idling, stepping on the gas to maybe it would straighten out I also got the code 36 hi-res fail too along with the 42 code. It is a new accel opti, put in on january so maybe it is junk.


Thanks

 

The IC circuit is the white wire from the PCM to the ICM. When cranking the engine, the white wire will have 1-4 volts AC. NOT DC signal on it. DTC41 indicates the line is open (floating) and 42 indicates it is low or shorted to ground. First thing to do is ohm it out to the black PCM connector pin 5. Disconnect the PCM before you ohm it.

If that all seems good, try tightening up the pin that plugs onto the ICM. Then get some readings at the ICM while cranking with the meter set to AC.

The DTC 36 is a high resolution feedback signal problem from the distributor. Check all the connections at the opti, at the test connection about 2 feet away from the opti and finally at the black PCM connector. There have been many opti/connector harnesses that have corroded. If the opti AND the connector harness is not replaced, this type of failure can occur.

Last, always include information regarding the vehicle and geographic location. This can help us in giving you information. A stupid example would be, the distributor. We know, from the codes you have that your vehicle is OBDI but in 95 the distributor was changed to a different drive setup and it included a vent system. It would help to know such things when helping you. Put the information about the vehicle in your signature and put your location in your profile. That way next time you don't have to repeat it all over again.

 

Had to bring this back...

So open means the wire is cut along the line and not connected to anything else? And grounded would mean it's connected to ground somehow through a short or something like that.

How can the car continue to run with an open EST circuit?

 

I am thinking that code pops up when I tried to start the car and it just immediatly died, or when I constantly had to keep tappin the gas. It turned out to the opti anyways that was screwin up. So I guess when the opti wasnt screwed that open or grounded short I supposedly had was working. So u are prolly right the car prolly cant run with a est short but it must have been intermediate and I only had it when the car would stall out and not run. When it would run the glitch must have been gone for that time.

 

41 and 42 often appear in conjunction with opti problems. It would not seem like they would (perhaps because the firing signals are being affected?), but I have seen enough posts to know that they do.

 

yah exactly like I did, U get those codes then you most likely have opti problems.