ABS problem
Q I have been having problems with the ABS on my 1996 Volvo 850 estate. I’ve tried connecting to the OBD-II socket using my laptop and ELM327 interface, but I cannot get them to communicate. I’m not sure if it’s an electrical problem (Pin 16 on the OBD-II socket is showing 12 volts) or a software issue. Do you have any idea what I could try? Or can you recommend an interface/ software combination which would work with my Volvo? Terence Nunn
A You do not mention the operating system you are using with your ELM327 interface, but it is possible that you will need to download the correct drivers to communicate with your Volvo. The ELM website does list the 1996 Volvo 850R 2.3 Turbo as being compatible with mode 1 (80000000) and mode 2 (04000018), but these are both for engine diagnostics. Mode 3 is for chassisrelated codes and this is not listed as being compatible with your Volvo.
From the data I have, your 850 may be fitted with a self-diagnostic unit under the bonnet. There should be two small boxes next to each other; unit A should have a black cover and unit B should have a grey cover. Unit A will have a small jump wire and a button under the cover, as well as an LED.
If this is the case, you can read off the codes as follows: place the jump wire in unit A into socket 3 in unit A, then turn on the ignition. Press the button once and the fault code should flash out. Once this has been recorded, depress the button once again and, if there is a second code, this will now display. If the same code is flashed out, then hold the button in for five seconds and release, three seconds after the button has been released the LED should illuminate. While the LED is illuminated, press the button again and hold for five seconds and release. The LED should now extinguish and the ignition can be turned off.
When all of the trouble codes are erased, the code flashed out should be 1-1-1. Once 1-1-1 is displayed, the ABS dash light should extinguish when the vehicle is driven at 25mph or higher.
If your Volvo is not equipped with the self-diagnostic box, it may require the dedicated Volvo break out box 951 1428 or the VIDA system to enable the codes to be read. It seems most of the code readers on the market do not guarantee compatibility with the Volvo 850 prior to 1998.
One of the common failures with the ABS fitted to the 850 is the pump and Ecu/combined module and it may be the case that the failure is preventing it from communicating with your system. In this case, ecutesting.com can check and repair the unit for £174.