how do i test the ignition control module
03-24-2005, 09:08 PM
#1
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Location: Aiken, Sc
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how do i test the ignition control module
like the title says. how do i test the icm? i know theres a way to do it with a multimeter but i font know which pins to test off of and what the range is
03-25-2005, 01:21 AM
#4
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Location: Aiken, Sc
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Re: how do i test the ignition control module
i need to know this befor i sink more money in this car and that not fix the problem. im at the point where im ready to sell this car and buy 2005 corvette
03-25-2005, 11:06 PM
#5
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Location: Texas
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Re: how do i test the ignition control module
Oreilly's here can test the ICM, and you are right they are hard to test, they dont have a connector that just hooks up right up to them. When I had mine tested they actually had to manually hook up wires to certain terminals to test.
03-26-2005, 05:48 AM
#6
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Re: how do i test the ignition control module
Start with the ign control signal on the white wire of the ICM 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.
One other thing, do yourself a favor and put the screen back in your MAF.
Dave
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.
One other thing, do yourself a favor and put the screen back in your MAF.
Dave
03-26-2005, 07:26 AM
#7
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Join Date: May 2003
Location: MO.
Posts: 452
Re: how do i test the ignition control module
Originally Posted by oneslowz28
i need to know this befor i sink more money in this car and that not fix the problem. im at the point where im ready to sell this car and buy 2005 corvette
04-17-2020, 06:55 AM
#9
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Join Date: Apr 2010
Posts: 35
Re: how do i test the ignition control module
Start with the ign control signal on the white wire of the ICM 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.
One other thing, do yourself a favor and put the screen back in your MAF.
Dave
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.
One other thing, do yourself a favor and put the screen back in your MAF.
Dave
what does that mean?
04-17-2020, 01:55 PM
#10
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,646
Re: how do i test the ignition control module
Always helps to know the year of the car.
Are you sure you probed pin “B”. Some of the factory wiring diagrams label the ICM connector pins as C-A-D-B, but the actual connector is correctly labeled A-B-C-D.
Better test guide from Shoebox:
4th Gen LT1 F-body Tech Articles
http://shbox.com/1/95_ign_system_schematic.jpg
Are you sure you probed pin “B”. Some of the factory wiring diagrams label the ICM connector pins as C-A-D-B, but the actual connector is correctly labeled A-B-C-D.
Better test guide from Shoebox:
4th Gen LT1 F-body Tech Articles
http://shbox.com/1/95_ign_system_schematic.jpg
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