Glow plug & traction control warning lights
My car is a 2005 Mk5 Volkswagen Golf TDI 1.9, engine code BKC, which has done 50,000 miles. There are two faults I need to address: 1: The glow plug light doesn't always come on with the ignition. If I switch off/ on a couple of times then it eventually does illuminate and the engine starts normally. When the light doesn't come on, there is no audible click. This happens on both cold and warm starts. Could this be the glow plug relay? VW'S parts people tell me this is more than just a relay as it is also a glow plug control unit, but I cannot locate it on the car – neither the Haynes manual nor handbook gives any clue. I found fusebox B beside the battery in the engine compartment, and it has three relay/control units – two blacklabelled 443 and one grey-labelled 458. 2: The traction control light is permanently on. This seems to be a common fault on the Mk5 Golf according to online forums and is caused by a faulty sensor in the ABS pump unit. BBA Reman apparently does a reasonably-priced refurbished unit that contains the sensor.
After removing and replacing the block on the ABS pump, I assume the brakes will require bleeding. Can I carry out this procedure without the VAG-COM tool by just using a standard pressure bleeder? Harry Coulter
First, thank you for providing the engine code – this helps in ensuring I supply the correct information. In answer to your first question, the glow plug relay should be located under the left-hand side of the dash panel. You will find a block of five relays and the glow plug control unit will be fitted below this in an additional relay carrier bracket.
I would also check that the glow plugs are operating correctly – if they have failed and are creating an open circuit, the light will not display correctly.
To test the glow plugs using an ohm-meter, first disconnect the leads. Then you'll need to place one probe on the terminal of the plug and the other to earth. You should get a reading of around 5 ohms. A high reading will indicate an open circuit.
The cause of the illuminated traction control light can be various failed components, including the brake light switch. This £10 switch controls far more than the rear brake lights – whenever we get a vehicle in the workshop with an ABS or ASR problem, the switch is the first component we change. It must be fitted correctly and this means not operating it until it is in position. It must be firmly turned into the bracket and will not operate correctly unless fully clicked in place.
If this does not cure your problem, I would get the system scanned for error codes, to ensure that the fault is the ABS pump and not an ABS sensor or similar component. If the vehicle does require a replacement ABS pump, then bleeding the brake system can be carried out in the conventional manner without the need for the VAG-COM system.