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No the alternator working or not should should not affect this one. OK the next thing I can suggest for this is more difficult to do - temporarily connect Central Warning Unit pins 19 & 20 (on the black connector) together (these are 2 Brown/Black wires) - not sure how easy this is to do in practice...
If the Brake Pad Light stays on after this it would seem to be either a Central Warning Unit issue or a Dashboard issue since this test will eliminate all the car wiring outside these 2 items. If this fixes it it suggests there is a wiring issue elsewhere on the car. lets see what happens to determine what is next.
No the alternator working or not should should not affect this one. OK the next thing I can suggest for this is more difficult to do - temporarily connect Central Warning Unit pins 19 & 20 (on the black connector) together (these are 2 Brown/Black wires) - not sure how easy this is to do in practice...
If the Brake Pad Light stays on after this it would seem to be either a Central Warning Unit issue or a Dashboard issue since this test will eliminate all the car wiring outside these 2 items. If this fixes it it suggests there is a wiring issue elsewhere on the car. lets see what happens to determine what is next.
Alan
okay. I’ll try to find the wiring diagram or PET to locate the CWS. If I remember correctly it is behind the DS foot rest somewhere?
That's where it is for most years. Its actually inside the footrest space - remove the footrest shell.
Alan
Yes Sir...Will do. Ran out of time today but on the agenda for tomorrow. Took a quick look. Hopefully it is self explanatory on how to remove the footrest. I found one bolt. I'm guessing there is another one or two.
Also, is it ok to go ahead and hook the brake pad sensors back up or do I need to wait until after I test the CWS? I'll take some pics during the process as well. Thanks, B
The footrest has a locating pin and perhaps just 1 bolt? - try moving/lifting it if you have removed a bolt. It doesn't matter for this test if the sensors are connected or not.
If you reattach the sensors check all the connecting points and local wiring for damage - pay special attention to the front left sensor - its the only one we didn't really eliminate in the previous test/
The footrest has a locating pin and perhaps just 1 bolt? - try moving/lifting it if you have removed a bolt. It doesn't matter for this test if the sensors are connected or not.
If you reattach the sensors check all the connecting points and local wiring for damage - pay special attention to the front left sensor - its the only one we didn't really eliminate in the previous test/
Alan
Hi Alan, here is a pic of the connector being jumped. Is this correct? Also another pic is of the front left brake pad sensor harness.
The proper test is with everything connected (bottom picture) and both brown/black wires connected (its the connector side that is important - the loom side goes back to the brake sensors).
With the black plug disconnected it goes out because there is nothing to drive the bulb. So actually that says its the CWS at fault not the dashboard. The CWS connection that illuminates the light is Pin 6 on the black connector - "Brake Pad" illuminated when its grounded. I'd say obviously that works - but you can test it.
Another test you can do for confidence in the sensor wiring is to (with all sensors connected) test for continuity between the 2 Brown/Black wires on the loom side. You should have connectivity until a brake pad sensor goes bad (detects excessive wear). Also test you do not have continuity to Ground on either wire.
OK - seems like it's definitely a problem in the CWS or dashboard then.
Alan
I have exactly the same problem : my solution was removing the brake pad warning bulb.
I did a test with 2 CWS units and both gave the same problem. So probably the CWS unit is just measuring too much resistance
in the circuit…
I have exactly the same problem : my solution was removing the brake pad warning bulb.
I did a test with 2 CWS units and both gave the same problem. So probably the CWS unit is just measuring too much resistance
in the circuit…
Its more than that here - since the sensing wires were shorted right at the CWS - the CWS has clearly failed - since there could not be less resistance outside the unit.
It may be a common failure mode for this controller with age perhaps - or just coincidence here. Generally failures in the brake pad warning system can more commonly be traced to mechanical or corrosion damage at the sensor connections at the wheels [or of course real issues with the pads: wrong pads installed w/ no sensors, not hooked up or truly worn pads].
Its more than that here - since the sensing wires were shorted right at the CWS - the CWS has clearly failed - since there could not be less resistance outside the unit.
It may be a common failure mode for this controller with age perhaps - or just coincidence here. Generally failures in the brake pad warning system can more commonly be traced to mechanical or corrosion damage at the sensor connections at the wheels [or of course real issues with the pads: wrong pads installed w/ no sensors, not hooked up or truly worn pads].
Alan
Alan,
I bypassed the brakepad circuit by bridging pin19 and 20 on the black connector of my CWUnit. It gave the same result. I did a test with a spare CWUnit and it gave exactly
the same problem….a little bit too much coincidence😬
Is there any way to verify the components on my CWunits ..,,is there a wire diagram of a CW unit?
Gerrit / Alan,
Did you manage to get a wire diagram of the CWU?
I have one on my desk with the large resistor on the PCB of the black connector broken & burned.
So I can't read the value of it.
07-21-2022, 06:14 PM
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