Code 31 - Theft Deterrent Signal missing

[ragrim]

Hi,

Ive just started getting Code 31 - Theft Deterrent Signal missing error and i havnt a clue what it means, nothing has changed in my car except it was sitting for 2 weeks without starting it and now this error has come up.

Can anyone shed some light on what causes it and how to get rid of it as my engine light is on constantly now.

 

[Brett_jjj]

Error code 31 should not make the engine light come on.Id be re checking for other logged errors as well.According to the workshop manual, code 31 will set if the Body Control Module or(BCM)(theft deterrent circuit) does not return a signal to the(Electronic Control Unit) or ECU when the ignition switch is switched on, to permit operation of the injectors.When this code is present there will be a one second delay in starter motor operation after turning the key to the start position.Some people think its a faulty ignition key or key reader that causes this,but if the key doesnt send a signal to the BCM at all, the engine wont even attempt to crank at all.It seems to be a faulty connection between the BCM and ECU that causes it.

 

[ragrim]

hmm that makes sense, i have noticed a delay when turning the key to when the engine starts, sometimes it can take 5 seconds for the car to start, but its very random..

i have had a code 33 logged aswell which was causing the engine light on, but i fixed that over the weekend and then cleared the error codes by leaving the battery off for a few hours, now only code 31 remains and the engine light is still on.

Should i start by check the connections on my BCM and ECU to fix it?

 

[Brett_jjj]

I am looking in the VS workshop manual ,but theres no code 33 on the VS models.Are you sure you are counting the flashes right?The codes go 31,32,35.These are the only error codes in the 30's on VS models.31 is the theft deterrent circuit,code 32 is airflow sensor,and code 35 is idle speed error code.No mention of 33.

 

[ragrim]

i may have got it wrong it could have been 35, i know the error was idle speed high, which i fixed by changing my idle air control valve.

 

[Brett_jjj]

Disconnecting the negative battery terminal for a couple of minutes will clear the errors,no need to leave it off for hours.Id clear the errors again and check all the wiring connectors by unplugging them and plugging them back in again.Do the ones under the bonnet and under the dash,especially the ones around the ECU area.Also after you have cleared the errors,try checking the codes again to confirm they have cleared properly,you should get a constant code 12 three times in a row flash up, which means theres no error codes set,which confirms they all cleared when the battery was disconnected.

 

[ragrim]

before i cleared it i was getting , 12 12 12, 31 31 31, 35 35 35. now i get 12 12 12, 12 12 12, 31 31 31

Ill check the connections to ECU and BCU this arvo and double check all connections are clean. Is it possible its to do with the ignition barrel? my ignition sticks on full when i start the car and have to manually turn it back to acc after starting car.

 

[Brett_jjj]

Im not sure but you never know,did the error code show up around the same time the key stuffed up?The ignition key(head) earths through the key stem and the lock barrel.

 

[bandit10]

VS V8 has a Code 33, must just be the V6 that has no code 33

Code 33 - MAP Sensor Signal - Voltage Too High

 

[Brett_jjj]

I probably should have mentioned before that it was the V6 workshop manual that I got the info from.I didnt even know they were different between the V6 and V8.