PDAS switch not working
02-19-2019, 07:01 AM
#1
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PDAS switch not working
I have been having problems with my ABS/PDAS and since taking it apart to change out the accumulator and booster pump I cant get the PDAS switch to work to bleed the diffs. When I put the ignition on the yellow light on the switch flashes for a brief second but wont do anything. It all worked before so I am confused and not sure where to look first.
I have bled the brakes, clutch, accumulator and pdas valves but wondering if the diffs need bleeding with a Bosch hammer to get them working again. Is it just air in the system making them not work or something more serious. Strange if it is as like I say it all worked fine before. I have changed out the switch with a known working one so that rules that out.
Any help would be much appreciated.
Cheers
Darryn
I have bled the brakes, clutch, accumulator and pdas valves but wondering if the diffs need bleeding with a Bosch hammer to get them working again. Is it just air in the system making them not work or something more serious. Strange if it is as like I say it all worked fine before. I have changed out the switch with a known working one so that rules that out.
Any help would be much appreciated.
Cheers
Darryn
02-19-2019, 08:02 AM
#2
Three Wheelin'
I would try to retrace your steps. Air in the system won’t keep the electronic solenoids from acting when you twist the switch. It’s going to be something electrical.
02-20-2019, 12:15 AM
#3
Rennlist Member
If you have access to a Hammer or PDT999 (?) then having access to the lock bleed function might help you diagnose. Actually if you own a C4 it's pretty useful to get the PDT999999 anyway. It's a good tool for accessing lots of the critical functions. Have you lost any ground connections during your repair work? Also check the connections to the actuators under the car as well...
Just some thoughts. Good luck!
Just some thoughts. Good luck!
02-20-2019, 02:08 PM
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Thanks for the replies. I have been over it all today and cant fault the wiring, as I only changed the pump and accumulator there isn't much in the way of wiring that could be wrong, I have even changed out the pump relays for good ones but to no luck.
One thing I have noticed is that now after I put the ignition on the pump will kick in for maybe up to a minute, then after maybe 5 minutes it will kick in again even when just sitting there. I am guessing there is a leak somewhere in the system but no fluid is leaking. If I am losing pressure could this be the reason the 4wd switch wont work? if there isnt enough pressure in the system the actuators may not have enough pressure to move the solenoids in the diff?
I am running out of things to look at now so maybe have to go and get it plugged in to diagnostics and see what it comes up with.
One thing I have noticed is that now after I put the ignition on the pump will kick in for maybe up to a minute, then after maybe 5 minutes it will kick in again even when just sitting there. I am guessing there is a leak somewhere in the system but no fluid is leaking. If I am losing pressure could this be the reason the 4wd switch wont work? if there isnt enough pressure in the system the actuators may not have enough pressure to move the solenoids in the diff?
I am running out of things to look at now so maybe have to go and get it plugged in to diagnostics and see what it comes up with.