1994 Toyota Camry Codes 12 and 41

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EVIDINHAJR
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  • 1 POST
I bought this Camry about a year and a half ago with a check engine light on problem. Erratic idle prompted me to take it in to the Dealer for servicing. Dealer diagnosed code 12 and 41. Recommended replacing the distributor, ignition coiil, plug wires and spark plugs, and throttle positon sensor. Check engine light still remained. Erratic operation still continued with addition of intermittant hard starting. Took it to another auto mechanic. Recommended replacing the distributor again. Mechanic did a check of signals sent from the distributor to the computer controlling idle rpm and fuel delivery. Did a wire harness check. Recommended testing and or rebuilding/replacing the main Engine computer (ECM). Sent ECU out to be repaired/rebuilt. Returned with the problem and some new ones. Car now stalss or dies out intermittently when at a stop. Sent ECU back to the rebuilder. Returned with the same problems. Took car to a local auto diagnostic sun center. Tech diagnosed all systems good with the exception of the computer. Distributor, starting/ignition, sensors, grounds systems and the wire harness circuitry are all doing what they are supposed to do whithin specs. How do I verify or correct this possible computer problem when the repair/rebuild folks say that the computer is fixed?
May 18, 2006 at 8:07 PM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
From the codes you must have the 2.2l as the 3.0 is ODB2

First of all there are no signals from the distributer to the ECU that controls fuel delivery and Engine idle. The ECU does this based on all sensor inputs with the distributer being only one of the signals used..

Code 12 is RPM sent from the distributer to the ECU

Code 41 is the throttle position signal sent to the ECU

There are two different ECU, on is a California and one is other. The RPM signal and TPS signals are used differently in the Calif. ECU.

I suspect you might have a mix up of ECU. I am looking at the schematics now and that is the only thing different and if you have the wrong ECU it will cause those codes to be set.

Let me know
May 20, 2006 at 2:09 AM

Suggested Repair

Verify that the installed ECM is the correct California or non-California unit for this Camry. A mismatched ECU uses the distributor RPM and throttle-position signals differently and can set codes 12 and 41. Confirm the correct ECU part rather than assuming the distributor directly controls fuel delivery and idle.

Conversation Summary

The owner of a 1994 Toyota Camry reported a persistent check-engine light, erratic idle, intermittent hard starting, and stalling at stops. Codes 12 and 41 remained after distributor, ignition, plug, wire, and throttle-position sensor work, and rebuilt ECUs did not correct it. A diagnostic shop found the other systems within specification and blamed the computer. The expert said the 2.2L uses code 12 for the distributor RPM signal and code 41 for the throttle-position signal, explained that the ECU controls fuel and idle from multiple inputs, and suspected a California versus non-California ECU mismatch.

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