Igniton Control Circuit (grounded curcuit)(bypass error)
where do i even start looking to solve this problem, its on my brothers '95 TA, in the steering column? i'm lost

thanks
Steve

 

Nope, not in the column. It has to do with the spark (ignition), not the ignition switch.

What are the symptoms? Does it run at all?

 

shoebox, you're the guy i was hoping would reply
yeah it starts (lil hard every now and then but nothing major) and runs fine, just throws a code and SES light, fans are always on but thats normal with a light, we had it scanned and cleared last night, came back in about 2 min. guy thought it might be the actual ignition switch so thats why i said that, only ignition upgrade we've done is put in a MSD coil and change out the plugs to NGK TR55's, everything else is stock if that helps any....

thanks
Steve

 

TTT where do i start to check

 

The PCM will set a 42 when the signal from the PCM to ICM has a problem, usually grounded. This signal is on the white wire of the ICM and goes to pin B and at the PCM is on the black connector pin 5. The first thing to do is disconnect both connectors and check continuity from pin B of ICM to pin 5 of the PCM connector. You may need a second wire to reach it with meter. Obviously if there is no continuity, you have a wire to fix.

If ok, connect both ends and put the meter on AC Volts. While cranking the engine, look at the signal on the white wire of the PCM. It should have between 1 and 4 volts AC on it. Remember to ground the black lead.

If no AC signal, pull the connector at the PCM (black connector) and check the signal coming out of pin 5. If there is no signal coming out of pin 5 then most likely (notice I said most likely), the PCM is bad.

If the AC signal is getting to the PCM on the white wire, you must now look at the signals from the ICM to the coil. Ignition off. Meter set to DC Volts. First check for a good ground to the ICM. Put a meter lead on the + battery terminal and probe the black wire pin C on the ICM with the other lead. It should show a full battery voltage (12 or more volts).

If not you have a bad ground.

Ignition on. Meter set to DC Volts. Now check the pink/black wire on pin A of the ICM and the white/ black wire on pin D of the ICM for battery voltage (12 or more volts) remember to ground the other lead.

If the voltage is there, the problem is the coil. If it is not on those 2 pins, you have to determine if the wire from the coil to the ICM is broken, or if the connectors are bad or the coil is bad.

Also if the voltage is not on those 2 pins, check the #11 fuse (10 amp) the supplies the ignition. If blown, no voltage either.

If the AC signal is getting to the ICM and the ICM has 12 volts on pins A and D, the ground is good to the ICM, and you still have no spark the ICM is probably bad.