After 1500 miles I'm finally getting around to hooking up cruise in my MK1 ALH swap.
It's had a brake switch trouble code accompanied with a flashing glow plug light forever. Brake lights functioned properly, and I could find no issues caused by the code, so I just ignored it.
16955
P0571 - 35-00* - Implausible Signal
Today I discovered the cause, or rather a symptom, probably not the root cause. The ECU thinks the brake pedal is depressed. I confirmed with VCDS that the cruise stalk is functioning properly, but cruise cannot be activated due to the phantom brake that the ECU sees.
T1 constant 12v
T2 dead with ignition off, constant 12 with ignition on
T3 dead with ignition off, 12v with brake pedal resting, dead with brake pedal depressed
T4 powered with brake pedal depressed
Wire 1 is obviously the power supply. Wire 4 is obviously brake light controller. Wire 3 seems to interact with the ECU, and it's behaviour would makee sense. The behaviour of wire 2 seems wrong. It powers up with the ignition, and seemingly has no interaction with the brake switch.
Can anyone explain a little more about the function and final destination of wires 2 and 3?
I should be able to look at a Bentley in a few days, but don't have access at this moment.
It's had a brake switch trouble code accompanied with a flashing glow plug light forever. Brake lights functioned properly, and I could find no issues caused by the code, so I just ignored it.
16955
P0571 - 35-00* - Implausible Signal
Today I discovered the cause, or rather a symptom, probably not the root cause. The ECU thinks the brake pedal is depressed. I confirmed with VCDS that the cruise stalk is functioning properly, but cruise cannot be activated due to the phantom brake that the ECU sees.
T1 constant 12v
T2 dead with ignition off, constant 12 with ignition on
T3 dead with ignition off, 12v with brake pedal resting, dead with brake pedal depressed
T4 powered with brake pedal depressed
Wire 1 is obviously the power supply. Wire 4 is obviously brake light controller. Wire 3 seems to interact with the ECU, and it's behaviour would makee sense. The behaviour of wire 2 seems wrong. It powers up with the ignition, and seemingly has no interaction with the brake switch.
Can anyone explain a little more about the function and final destination of wires 2 and 3?
I should be able to look at a Bentley in a few days, but don't have access at this moment.