85 Check Engine Code 42
Thread Starter
8th Gear
Joined: Apr 2004
Posts: 8
Likes: 0
From: NY
85 Check Engine Code 42
My 1985 with 148K miles has been setting a code 42. Sometimes the check engine light comes on right away, other times the car starts fine and no code, then all of a sudden it may stall and then boom, solid code 42. What's been done recently (because of a different code):
1- New egr valve
2- New egr solenoid
3- Cleaned under throttle body, etc.
After this service, car sets a code 42. Technician has traced all the wires in the harness to make sure there's no opens or shorts. Computer was replaced last year. They just put in a new ignition module this morning, still the same results. They don't know what to do aside from replacing the computer again. I (and the dealer) don't want to keep throwing parts at it. Please, any suggestions??? I haven't been able to drive it all summer.
1- New egr valve
2- New egr solenoid
3- Cleaned under throttle body, etc.
After this service, car sets a code 42. Technician has traced all the wires in the harness to make sure there's no opens or shorts. Computer was replaced last year. They just put in a new ignition module this morning, still the same results. They don't know what to do aside from replacing the computer again. I (and the dealer) don't want to keep throwing parts at it. Please, any suggestions??? I haven't been able to drive it all summer.
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
Originally Posted by 85_bronze
My 1985 with 148K miles has been setting a code 42. Sometimes the check engine light comes on right away, other times the car starts fine and no code, then all of a sudden it may stall and then boom, solid code 42. What's been done recently (because of a different code):
1- New egr valve
2- New egr solenoid
3- Cleaned under throttle body, etc.
After this service, car sets a code 42. Technician has traced all the wires in the harness to make sure there's no opens or shorts. Computer was replaced last year. They just put in a new ignition module this morning, still the same results. They don't know what to do aside from replacing the computer again. I (and the dealer) don't want to keep throwing parts at it. Please, any suggestions??? I haven't been able to drive it all summer.
1- New egr valve
2- New egr solenoid
3- Cleaned under throttle body, etc.
After this service, car sets a code 42. Technician has traced all the wires in the harness to make sure there's no opens or shorts. Computer was replaced last year. They just put in a new ignition module this morning, still the same results. They don't know what to do aside from replacing the computer again. I (and the dealer) don't want to keep throwing parts at it. Please, any suggestions??? I haven't been able to drive it all summer.
Thread Starter
8th Gear
Joined: Apr 2004
Posts: 8
Likes: 0
From: NY
I mentioned that they already replaced the ignition module (just today) and the problem still exists. The tech says it's either the PROM, Calpak or the computer.
Last edited by 85_bronze; Aug 30, 2005 at 08:02 PM. Reason: typo
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Code 42- This code will be set when the engine is running at 600 rpm or greater, and there is no pulse on the white wire from the ecm to the ignition module for more than 200ms (milliseconds). Common causes for this code include bad connections, frayed wiring, or broken wires such as the tan/black (ecm pin D5) purple/white( ecm pin B5) or white wire (ecm pin D4). Check your wiring carefully along with the connections back to the ecm.
Thread Starter
8th Gear
Joined: Apr 2004
Posts: 8
Likes: 0
From: NY
The tech at the dealer checked and traced all the wiring. He said there were no shorts or opens in the wiring even after jostling the wires around. Since the ECM was replaced in April, 2004, he figured the ignition module in the distributor was the most likely cause. Now that the ignition module has been replaced and the problem still exists, he says the only other thing possible is either the ECM itself or the PROM or CALPAK chips in he ECM. Based on his testing, I have to believe that the wiring is ok. Is there any other possibility that can cause the code? Where is the best/cheapest place to get a computer and the chips that go with it?
Last edited by 85_bronze; Aug 31, 2005 at 10:22 AM. Reason: clarification of when ecm was replaced
