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.

[bandit10]

there are a few codes different from V6 to V8, the V8 also has a code 34

[benno9911]

Mine has a code 31 cause my key been playing up

[ragrim]

Mine has a code 31 cause my key been playing up

what do mean playing up? my key seems to not work sometimes, i stand next to the car pressing the button and walking around the car and 5 minutes later itll lock/unlock

[bandit10]

what do mean playing up? my key seems to not work sometimes, i stand next to the car pressing the button and walking around the car and 5 minutes later itll lock/unlock

You can replace the battery in the key head, that should fix this problem.

There is a how to on this somewhere on here.

[benno9911]

well it unlocks the car fine it when you turn the key to start it nothing happens but i have to lock and re-unlock it then turn the key and it starts

[cbv85l]

G'day Guys,
I have a vz ss crewman which came up with svs (service vehicle soon) which is actually a non emissions related fault, and very low fuel alarm on the dash. Fuel pump primes ok, starts and runs for 2 seconds, then shuts down.
I tried both keys - no change. Disconnected the battery for 10 mins - no change. Charged the battery for 6 hrs out of the vehicle, put back in and no change.
Eventually got hold of a scanner and found fault code p1626- theft deterrent fuel enable signal not received.
I have read on US sites relating to c5 corvette that this could be a bad connection or broken wire between bcm and ecu.
Has anyone else had this problem, any info on a fix would be appreciated. Car is a daily driver and currently stuck in work car park.

[Brett_jjj]

It definitely sounds like that could be the problem,no communication between the BCM and ECU.The ECU has to request an "OK to start" signal from the BCM,the BCM then checks the coded ignition keyfob to see if its right to give the ECU the "OK to start" signal,then if the ignition keyfob's security code matches the BCM's security code,the BCM then tells the ECU its ok to start.. Id be getting hold of a good wiring diagram and testing the wiring and connectors between the ECU and the BCM.

[cbv85l]

thanks mate,
I have gone through and checked connections, all seemed ok, unplugged and reseated them all, couldn't find any broken wires etc,
now just have to get the wiring diagram,
I found on ebay there is a bcm bypass for about $6 from the US. might be my best option,

[Brett_jjj]

You will probably need to find which wire is the serial (data) wire that runs between the BCM and ECU, and test it to see if its connected and not broken etc.It could also be a faulty ECU or BCM but you will need a scantool (Tech2) to access the BCM to see if there are any BCM error codes logged..These BCM error codes are different from the ECU codes..

[cbv85l]

Ended up towing to Auto elect, hes had a look and quoted $1000 to send ECU and BCM to Melbourne for repair. Have now relocated the vehicle to Holden dealership after a lot of discussion about what is covered under my extended warrinty agreement. they have agreed to cover the ECU to the value of $1000 but the BCM is not covered, as mentioned earlier the tech 2 revealed the PIM (powertrain inferface module) is the actual problem. $340 plus another week out of action, better than $1000 that would not have fixed the problem

[DK101]

what do mean playing up? my key seems to not work sometimes, i stand next to the car pressing the button and walking around the car and 5 minutes later itll lock/unlock

My 304 VR does this too... Has an aftermarket alarm kit fitted and has done since I got it more than a year ago... Been getting Err 31 since the day I bought it and quite often she wont unlock, I attributed it to the hackjob they must have done with the aftermarket alarm and immobiliser, but if you're having the same issue on the stock unit, then maybe its a problem in the BCM?

[DK101]

You can replace the battery in the key head, that should fix this problem.

There is a how to on this somewhere on here.

I have replaced the batteries in my standard Holden key head and the Fob which controls my aftermarket alarm... Still no fix... Might I add that sometimes it works perfectly fine, but most times it's extremely frustrating, normally when I'm in a hurry it will stuff me around

[cbv85l]

Back on the road, Holden replaced the powertrain interface module $340 including labour, they ordered it 3pm Fri. got the ute back Mon arvo. I think this is a pretty good outcome.
If I had left it up to the auto elect I would have been up for close to $2000 I rekon.