If you're messing with brake light switches, make sure you follow the fitting procedure. For the 4 pin "new" style, this is it:
The brake light switch must not be operated while the brake
light switch is being installed. The brake pedal may only come
into contact with the push rod head of the brake light switch
during the whole installation process.
– Guide the brake light switch through the assembly aperture
and push it with the push rod head against the brake
pedal.
- Then turn the brake light switch through 45° to the right
until it noticeably engages
You identify new style switches by the different coloured tip on the pushrod. (white part)
There is a procedure for the old type, but to be honest, if you take it out, I'd just bin it and get a new one. Personally, I wouldn't bother with the generic ones because the design is questionable enough as it, never mind when its been "optimised" by a patent part maker. Real ones are not too expensive from the dealer, or dealers trading on eBay. For completeness, the procedure for the
OLD switch only (Taken from Golf 4 manual but I believe it is the same, please correct if wrong
).
Before installing, pull plunger out fully.
– Push brake pedal down as far as possible by hand.
– Guide brake light switch through fitting hole and reinstall by
turning 90° to right.
– Release brake pedal.
– Fit brake light switch connector.
– Check function of brake light.
– After adjusting the brake light switch check whether the brake
pedal is on the end stop (rest position).
Can the people having this issue, with VCDS, post Autoscans? Makes it a lot easier to diagnose
As for the issue at hand, people with VCDS, could you post Autoscans? That gives logs of all modules and is much more helpful when identifying issues.
@datsundrew when you did you scan, did you check the DTC memory in the "Engine" block in VCDS? The fault code is telling you there is fault code logged in the ECU that it wants you to check.
@Robin_Cox That first error I would guess is something to do with cooling fan. The last error (01314) I assume is actually being triggered by (17961). The sporadic communication errors are possibly incidental, they could come from the radio beng removed for example. Clear all the errors and see what comes back.
Assuming brake light switches, sensors, etc. is all okay, I would say there are three distinct failure categories:
1. ABS or ECU dry joint. ABS and ECU talk over CAN bus, if there is a dry joint in one of these modules, they may occasionally lose connection and cause these errors. Most module should be repairable by soldering, but to be honest it would cheaper to get a good used part in most cases. In these situations, you will have intermittent communication errors logged in one or both modules, and possibly the dash.
2. Wiring fault - "Simple", a wiring fault with power or powertrain CAN. Look at the loom for damage and check earths. You need to check between the ECU, ABS and Dash.
3. Dash/Gateway dry joint - The ABS and ECU CAN bus also connects to the gateway in the dash, if you have dry joints or connection issues, the dash will show an error because it has lost connection with the ABS controller. This
should generate an error in the dash stating that it has lost connection. If it were a fault on the dash end, I might expect to momentarily see a glitch with the Tachometer or Speedometer when the connection drops.
With autoscans it might be easier to say that "x" pattern of faults points to an issue with "x" thing.
