2012 Volvo VNL 780 I was told by a mechanic that when the TCS light is on (and dash light does not turn it off by pushing the toggle switch) that the air switch on the lower left firewall inside the cab is bad. But I can’t find anyone that knows which one of these air switches is the one for TCS. Does anyone on here know I have attached a picture and all 4 air switches have the same part number Thanks
Not necessarily your problem, but either of the 2 pictured could be. Luckily for you they are the same part # from Volvo. Better to get diagnosed with Bendix Acom software first.
Mechanic didn't tell you whole truth. TCS light could be on for many reasons. Steering position sensor. Yaw sensor Valves electrical malfunction Brake demand air pressure sensor. There is tags attached to the sensors pigtails. Two sensors for PRIMARY and SECONDARY. One sensor is for APPLIED BRAKE PRESSURE and one for rear airbags pressure to sense load. Manifold might be different from year to year but I believe right top one is for rear airbags.
Ok thanks Yes I agree it could probably be related to something else. The mechanic said that all the trucks he has worked on with this problem it has always been this air switch. Unfortunately only one tag has readable print the other tags are just white. Going by your description of the switches I’m still not sure which one would control OR effect TCS light. But thanks for your input
Mechanic said........... You need to know exactly code to figure out what is wrong. Did you check Diagnostics menu/View active faults/ Brake ECU for any codes? Or you need to diagnose it with ACom for codes.
you would need to have some sort of bendix software to be able to get to the bottom of this most of the time there is a calibration sequence after you install these switches and there is a few air switches that could do it, like applied brake psi, suspension psi, applied trailer brake psi, and parking brake psi. that being said there is no real way to tell unless you have software replace all 4 and try calibration sequence and see if it goes off but you will spend the $$ $ in parts that way, you can buy 2 and alternate till light shuts off. but not really many other options besides this.
Ok thanks for the insight. I was just going to buy all 4 switches but at $90 each I was hoping it would be easier to identify the correct one. —— silly me ——. Easier—- HA
