1990 VATS / CCM testing
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Heel & Toe
Joined: Nov 2024
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1990 VATS / CCM testing
New to the forum and the C4 platform. Picked up a hard luck 1990 L98 that had no keys so I installed a new ignition switch, now need to bypass the VATS with a resister at the 2-pin connector. Tried all 15 resisters per the procedure but still no luck. My ohm meter shows 4.27k ohm resistance between the CCM module WC12 pin (purple/yellow wire to ignition switch) and ground at all times. Is that normal or is the CCM fried internally?
If the CCM is bad I'll probably bypass VAT with a fuel relay and EEC fuel enable mod (or reprogram)..
If the CCM is bad I'll probably bypass VAT with a fuel relay and EEC fuel enable mod (or reprogram)..
Melting Slicks
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Thread Starter
Heel & Toe
Joined: Nov 2024
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Www.tunedperformance.org has a vats delete chip. Just need to provide your chip letter code.
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Heel & Toe
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Melting Slicks
Joined: Nov 2016
Posts: 2,216
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From: So Cal
2023 C4 of the Year Finalist - Unmodified
Not true. Perhaps the 2-3 guys left here still posting that are tech savy re VATS have become weary of writing it out every few weeks?
Turn the key to RUN. Is the SECURITY light solid-ON? (Or possibly flashing in groups of 3 simultaneously with a SYS message?). If = YES, the CCM is not receiving the correct resistance (which you know), but the CCM is functioning.
Recovering the correct resistance can be fussy. You probably "missed" it during your first attempt. How long did you wait between tries? There is another possibility in a 1990. For 1990, after the 3rd "wrong resistance", the wait time becomes 10 minutes before the next attempt. This goes away sometime later in 1990, but affects early 90s. I just wait 10 minutes between attempts. You can also use the onboard diagnostics to read the resistance A/D counts and compare the reading to a table to be sure your test resistance is within the parameters for that particular key-code.
Purchase a signal generator, bypass the starter relay, and move on.
Turn the key to RUN. Is the SECURITY light solid-ON? (Or possibly flashing in groups of 3 simultaneously with a SYS message?). If = YES, the CCM is not receiving the correct resistance (which you know), but the CCM is functioning.
Recovering the correct resistance can be fussy. You probably "missed" it during your first attempt. How long did you wait between tries? There is another possibility in a 1990. For 1990, after the 3rd "wrong resistance", the wait time becomes 10 minutes before the next attempt. This goes away sometime later in 1990, but affects early 90s. I just wait 10 minutes between attempts. You can also use the onboard diagnostics to read the resistance A/D counts and compare the reading to a table to be sure your test resistance is within the parameters for that particular key-code.
Purchase a signal generator, bypass the starter relay, and move on.
Thread Starter
Heel & Toe
Joined: Nov 2024
Posts: 20
Likes: 0
Thread Starter
Heel & Toe
Joined: Nov 2024
Posts: 20
Likes: 0
Not true. Perhaps the 2-3 guys left here still posting that are tech savy re VATS have become weary of writing it out every few weeks?
Turn the key to RUN. Is the SECURITY light solid-ON? (Or possibly flashing in groups of 3 simultaneously with a SYS message?). If = YES, the CCM is not receiving the correct resistance (which you know), but the CCM is functioning.
Recovering the correct resistance can be fussy. You probably "missed" it during your first attempt. How long did you wait between tries? There is another possibility in a 1990. For 1990, after the 3rd "wrong resistance", the wait time becomes 10 minutes before the next attempt. This goes away sometime later in 1990, but affects early 90s. I just wait 10 minutes between attempts. You can also use the onboard diagnostics to read the resistance A/D counts and compare the reading to a table to be sure your test resistance is within the parameters for that particular key-code.
Purchase a signal generator, bypass the starter relay, and move on.
Turn the key to RUN. Is the SECURITY light solid-ON? (Or possibly flashing in groups of 3 simultaneously with a SYS message?). If = YES, the CCM is not receiving the correct resistance (which you know), but the CCM is functioning.
Recovering the correct resistance can be fussy. You probably "missed" it during your first attempt. How long did you wait between tries? There is another possibility in a 1990. For 1990, after the 3rd "wrong resistance", the wait time becomes 10 minutes before the next attempt. This goes away sometime later in 1990, but affects early 90s. I just wait 10 minutes between attempts. You can also use the onboard diagnostics to read the resistance A/D counts and compare the reading to a table to be sure your test resistance is within the parameters for that particular key-code.
Purchase a signal generator, bypass the starter relay, and move on.
Melting Slicks
Joined: Nov 2016
Posts: 2,216
Likes: 3,045
From: So Cal
2023 C4 of the Year Finalist - Unmodified
If anything, I would think you will see a voltage to ground with the key in RUN. Again, I'm not sure what the voltage should be, but there should be some. Possibly 5V.
Because you have the solid-on SECURITY light, the CCM is functioning. If you access the A/D counts, they will be "255" which is open circuit.
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Heel & Toe
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Melting Slicks
Joined: Nov 2016
Posts: 2,216
Likes: 3,045
From: So Cal
2023 C4 of the Year Finalist - Unmodified
I don't see a direct correlation between the table I have and what you have. But try key code #12, 6,040 Ohms first. It wasn't code #12, but he found the code.
Last edited by IHBD; Nov 19, 2024 at 10:46 PM.
Melting Slicks
Joined: Aug 2011
Posts: 2,844
Likes: 176
Not true. Perhaps the 2-3 guys left here still posting that are tech savy re VATS have become weary of writing it out every few weeks?
Turn the key to RUN. Is the SECURITY light solid-ON? (Or possibly flashing in groups of 3 simultaneously with a SYS message?). If = YES, the CCM is not receiving the correct resistance (which you know), but the CCM is functioning.
Recovering the correct resistance can be fussy. You probably "missed" it during your first attempt. How long did you wait between tries? There is another possibility in a 1990. For 1990, after the 3rd "wrong resistance", the wait time becomes 10 minutes before the next attempt. This goes away sometime later in 1990, but affects early 90s. I just wait 10 minutes between attempts. You can also use the onboard diagnostics to read the resistance A/D counts and compare the reading to a table to be sure your test resistance is within the parameters for that particular key-code.
Purchase a signal generator, bypass the starter relay, and move on.
Turn the key to RUN. Is the SECURITY light solid-ON? (Or possibly flashing in groups of 3 simultaneously with a SYS message?). If = YES, the CCM is not receiving the correct resistance (which you know), but the CCM is functioning.
Recovering the correct resistance can be fussy. You probably "missed" it during your first attempt. How long did you wait between tries? There is another possibility in a 1990. For 1990, after the 3rd "wrong resistance", the wait time becomes 10 minutes before the next attempt. This goes away sometime later in 1990, but affects early 90s. I just wait 10 minutes between attempts. You can also use the onboard diagnostics to read the resistance A/D counts and compare the reading to a table to be sure your test resistance is within the parameters for that particular key-code.
Purchase a signal generator, bypass the starter relay, and move on.
Melting Slicks
Joined: Nov 2016
Posts: 2,216
Likes: 3,045
From: So Cal
2023 C4 of the Year Finalist - Unmodified
I put the signal generator in my 90 under the RH dash. All three circuits are right there. The dk blue wire is in one of the ivory colored 10-cavity connectors. Hot in RUN (pink/blk) is also in the same connector. Ground is easy, I used the screw in the A-pillar.
Last edited by IHBD; Nov 19, 2024 at 10:45 PM.
Team Owner
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The selection 8,9,7,10,6,11,5 etc I mentioned on this forum several years ago - that poster seems to have liked it!!!!
Thread Starter
Heel & Toe
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I put the signal generator in my 90 under the RH dash. All three circuits are right there. The dk blue wire is in one of the ivory colored 10-cavity connectors. Hot in RUN (pink/blk) is also in the same connector. Ground is easy, I used the screw in the A-pillar.
Terrible detail. The pink/blk and dk blue wires in the 2-cavity connector on the right were removed from the 10-cavity on the left. The 3 wires from the signal generator are to the dk blue in the left connector, and the red power wire is tapped to a jumper between the two connectors. I don't like to cut wires, I do it this way by de-pinning what I need, and adding connector shells as necessary.
Terrible detail. The pink/blk and dk blue wires in the 2-cavity connector on the right were removed from the 10-cavity on the left. The 3 wires from the signal generator are to the dk blue in the left connector, and the red power wire is tapped to a jumper between the two connectors. I don't like to cut wires, I do it this way by de-pinning what I need, and adding connector shells as necessary.