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Error code 41 check CAM sensor circuit

Tiny
CHARLES THOMAS2
  • MEMBER
  • 1993 BUICK PARK AVENUE
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 1,478,970 MILES
When checking cam sensor circuit found wiring harness for the cam sensor, crank sensor and the ignition control module bad. Removed harness and made new harness with new connectors. Installed harness and checked cam sensor circuit found power ground and a signal at the connector. When I installed the cam sensor on to the connector I saw A drop in the signal that goes to the computer. I replaced the cam sensor thinking it was causing the code, but I was wrong. I checked the internal magnet on the cam in the engine it was there and double checked harness and connectors found nothing wrong. Removed computer and did a visual inspection of computer and connectors looks okay. I need a wiring diagram and pin locations on computer in so I can check computer and harness. Please any help is needed.
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Wednesday, March 27th, 2019 AT 9:32 PM

13 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

I was unable to find a PCM Pinout diagram for you, but I was able to get a PCM wiring diagram that does have the connector and pin numbers for the PCM as well as wire color and where there going to. I have included them in the diagrams below. I blew them up as much as I could for you so each diagram is cut up into thirds. I hope this helps, and let us know if there is anything else we can help you with.

Thanks,
Alex
2CarPros
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Thursday, March 28th, 2019 AT 6:09 AM
Tiny
ASEMASTER6371
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Good morning,

Just to add to Alex's response, I attached a picture of the location of the cam sensor for you.

Check the harness carefully for any damage. In the old engines, there is a magnet on the cam gear that the sensor runs across and at times the magnet falls off and will set this code.

Also, if you have a worn timing chain, the cam and crank sensor are not lining up and this could be an indication of a worn timing chain.

Roy

CIRCUIT DESCRIPTION:
During cranking, the ignition module monitors the dual crank sensor sync signal. The sync signal is used to determine the correct cylinder pair to spark first. After the sync signal has been processed by the ignition module it sends a fuel control reference pulse to the PCM. When the PCM receives this pulse it will command all six injectors to open for a (priming) shot of fuel in all cylinders. After the priming, the injectors are left "OFF" for the next six fuel control reference pulses (two crankshaft revolutions) from the ignition module. This allows each cylinder a chance to use the fuel from the (priming) shot. During this waiting period, a cam pulse will have been received by the PCM. Now the PCM begins to operate the injectors sequentially, based on true camshaft position. However, if the cam signal is not present at start-up a code 41 will be set and the PCM will start sequential fuel delivery in any old random pattern. The engine has a 1 in 6 chance that fuel delivery is correct.

Code 41 sets when the following condition exists:

Cam sensor signal not received by by the PCM for five seconds while engine is running.
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Thursday, March 28th, 2019 AT 6:38 AM
Tiny
CHARLES THOMAS2
  • MEMBER
  • 7 POSTS
Thanks for the information. I have a new engine and I checked the internal magnet is was okay. After I installed the cam sensor pig tail code 41 came up. Checked cam sensor circuit found bad wiring harness replaced the harness and the cam sensor still have code 41. Looking for wiring diagram of the computers harness under dash to use to help check computers harness that might be the cause of the code 41. Starts up and runs but idles rough and stumbles sometimes. Need to find the cause of the error code 41.
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Thursday, March 28th, 2019 AT 8:30 AM
Tiny
ASEMASTER6371
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Alex provided you with the wiring diagrams of the system.

You need to trace the wires from the cam sensor to the ECM to be sure there is no open circuit.

You should have a scan tool to read the OBD1 system as you could monitor the voltage from the sensor to the ECM.

Roy
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Thursday, March 28th, 2019 AT 8:36 AM
Tiny
CHARLES THOMAS2
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  • 7 POSTS
Thanks for the wiring diagrams will be helpful when checking.
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Thursday, March 28th, 2019 AT 8:42 AM
Tiny
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Keep us updated.

Roy
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Thursday, March 28th, 2019 AT 8:43 AM
Tiny
CHARLES THOMAS2
  • MEMBER
  • 7 POSTS
Removed computer and checked wiring harness and found that all the wires have good continuity. Then I did a by pass test and checked the ref signal with a test light. With KOEO ref signal was 05.8 to 00.1, but when I connected the cam sensor the signal went down 05.8 to 02.8. What is causing the voltage drop? Is it the computer the ignition module or something in the wiring harness?
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Sunday, March 31st, 2019 AT 12:04 PM
Tiny
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That is the signal you measured back to the ECM.

That voltage is high. It looks like you need an ECM.

Roy
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Sunday, March 31st, 2019 AT 12:24 PM
Tiny
CHARLES THOMAS2
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Thanks for all the info Roy.I double checked all the work harness replaced & all connections are good. Computer looks like the problem is it the mem-cal inside or the computer would like the info on how to test computer and find out the problem and repair computer instead just replacing it.I am always up for a challenge.
Thanks everyone for help
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Sunday, March 31st, 2019 AT 5:09 PM
Tiny
ASEMASTER6371
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You need special equipment to test it.

Yes, memcal and the prom are inside.

$98.00 at rockauto.

Roy
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Sunday, March 31st, 2019 AT 5:15 PM
Tiny
CHARLES THOMAS2
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Got a good deal on all four motor mounts for $85.00 at rockauto the price is always right, but somethings I have to see before I buy. On the hunt for a computer this sounds like fun?
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Sunday, March 31st, 2019 AT 5:42 PM
Tiny
ASEMASTER6371
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Good.

Keep us updated.

Roy
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Sunday, March 31st, 2019 AT 5:44 PM

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