Code 31, what's the impact of it? (2 problems actually)

[Robm3]

Hi,
Problem #1. I'm getting a code 31 on my LT5 which is the Cam Shaft sensor but it doesnt seem to be effecting the running of the motor at all.
I've not done the testing as to if it's an ECU fault or not but just wondering what the impact of this would be on day to day running ('spose it's just a slight lose of power).

Problem #2 My Power Mode is working intermittently, getting power through the Valet Switch okay but the second row of injectors just aren't firing up consistantly. I'm wondering if the issue is related to problem #1

Any ideas?

Thanks Lads.

Robin

(PS the engine is actually in an Ultima GTR)

Robin, code 31 is for the Cam Sensor. The electronics use the sensor to sync up the ignition with the crank. When it is not working correctly, the SES light comes on, and then the injection system is firing in "batch" mode. This would be the reason why your secondaries are not working.


Possible causes:
Faulty Ground
Faulty Connection
Bad ECM
Bad Cam Sensor

[Robm3]

Originally Posted by Jeffvette

Robin, code 31 is for the Cam Sensor. The electronics use the sensor to sync up the ignition with the crank. When it is not working correctly, the SES light comes on, and then the injection system is firing in "batch" mode. This would be the reason why your secondaries are not working.


Possible causes:
Faulty Ground
Faulty Connection
Bad ECM
Bad Cam Sensor

Right then, I have the manual and it says to check the ECU when running to see if a current is coming through (Brown plug, pin 3 from memory). Can I pull the whole 'Brown' plug when the engine is running though? or do I need to just take out pin 3?

The manual then says if there is a fluctuating current coming through it's your ECU that's the issue.

I'm hoping there's no current then as I'm guessing a sensor or connection is an easier fix. Anyhow I'll have a play around with it tomorrow.

Thanks for the info Jeff

Originally Posted by Robm3

Right then, I have the manual and it says to check the ECU when running to see if a current is coming through (Brown plug, pin 3 from memory). Can I pull the whole 'Brown' plug when the engine is running though? or do I need to just take out pin 3?

Unplug the brown connector first. Then probe. With the brown connector unplugged the vehicle will not start. Do not unplug it with the vehicle running.

Thanks for the info Jeff

No problem.

[Robm3]

Originally Posted by Jeffvette

Unplug the brown connector first. Then probe. With the brown connector unplugged the vehicle will not start. Do not unplug it with the vehicle running.



No problem.

Jeff,
Sorry to be a pain but just to be sure,
step 1. unplug the brown plug and connect probe
step 2. then turn the engine over?
Presume it won't start as you say but will show a reading?


Manual is a little unclear as it says 'test with engine running' naturally that's a little tricky if you can't unplug the brown plug when running although can always 'splice' into the wire and test.

What book are you using?

Step 1:
Engine idling is code 31 present

If yes

Step 2
Ignition off
Disconnect brown connector
Probe D3 for voltage
Crank engine
Did DVM display 0-5 volts

Step 3
Ignition off
Disconnect cam sensor
Connect test light between terminal A & C of harness
Ignition on
Is test light on


Step 4
Connect test light between A and ground
Is test light on

[Tyler Townsley]

Long ago when mine threw a 31 it was the ECM not the sensor. You might have to borrow an ecm to check it out.

Tyler