BRAKE AND SIGNAL LIGHT TROUBLESHOOTING

Everything below applies to systems with the VW turn signal switch.

QUICK PRELIMINARY CHECK:

  • If neither brake light works, go here.
  • Check all the connections to the signal switch and trailer relay.
  • Turn on the parking lights.  Make sure that each light is equally bright (side-to-side). The signal filament is brighter than the parking light filament, so if one light is "extra" bright the bulb may be inserted 180 degrees out in the socket, or the contact plate in the light may be reversed.  

    To reverse the contact plate for the front parking light with staggered pin bulbs:

    Remove the lense and the bulb
    Pull back the boot as far as possible.  Some boots require that you remove the parking light completely.
    Push the wires into the back of the light housing.
    Turn the contact plate 180 degrees and engage the tangs as you pull the wires out.

    To reverse the contact plate for the rear round parking lights with staggered pin bulbs (You can simply reverse the leads on the rear rectangular lights):
    Remove the lense and the bulb
    Push the wires into the back of the light housing.
    Turn the contact plate 180 degrees and engage the tangs as you pull the wires out.
  • If you don't have brake and signal lights on one side, disconnect the red and yellow (or green) wires from the light.  With the parking light switch on, touch the red wire to each connection on the light.  One connection should be bright, the other less bright.  Connect the red wire to the dimmer connection and the other wire to the brighter connection.  More possibilities here.
  • Use only a Signal Stat brand flasher, #180 (it comes with the kit). Some others don't consistently indicate flashing on the dashboard, or may not flash at all.


This section assumes that everything correctly functioned after initial assembly, but now there's a new problem.

  • Some tests require a test light or a Volt/Ohm meter (VOM), but you may not need one initially.
  • The signal and brake lights only work with the ignition switch on, so all the signal tests below assume that.
  • Check all the fuses first.  Note that the brake lights are fused by the top fuse on the driver's side fusebox.  The signals are fused by the 4th fuse down (passenger's side) on the firewall.  If necessary, replace either with a 15A AGC.  
    Each rear light also has a separate fuse on a bracket underneath the steering column.    If necessary, replace with a 4A fast-blow AGC type.

What is wrong?


CONDITION A:
No signal light on one side, but you have the opposite signal, plus brake lights on both sides.

Check the front signal light.  (Sometimes the a bad front light will prevent the rear from working.)

Switch the #7 yellow and #7 green wire where they go into the 4-way connectors.

Try the signals in both directions.  

  • If your bad side (left/right) is now blinking (the wand action will be reversed), the problem most likely a bad column switch.  If you have a VOM, test the continuity between the B/W/G wire and both the B/W and B/G wires.  The B/W wire corresponds to the left side, the B/G wire to the right.
  • If the signal switch checks OK, replace the signal(trailer) relay.


CONDITION B:
No
signal lights on either side, but you've got brake lights on one or both sides.

  • Check the fuses as described above.
  • Replace the flasher.  Remember that some flashers don't work well with this system, so try to stay with the Signal-Stat brand.
    or test :
    Bypass the flasher by connecting a power wire (for instance #8 Violet) to the B/W/G wire from the signal switch.  (Remember that the ignition switch must be on for this.)  If the signal lights work, (they won't flash) the flasher is bad.  If the signals still don't work -
  • Test the signal switch with a VOM.
  • Check the front signal lights.  (Sometimes the a bad front light will prevent the rear from working.)
  • If the signal switch works, replace the signal(trailer) relay.


CONDITION C:
You've lost both the signal and brake light on one side only.

Check the fuse under the steering column.  

Test the connection to the rear as described below.

If the connection to the rear is OK:
Switch the #8 yellow and #8 green wire where they connect to the fuses underneath the steering column.

Try the signals in both directions.  

  • If your bad side (left/right) is now blinking (the wand action will be reversed), the problem most likely a bad column switch.  If you have a VOM, test the continuity between the B/W/G wire and both the B/W and B/G wires.  The B/W wire corresponds to the left side, the B/G wire to the right.
  • If your bad side is still bad (the wand action will be reversed), the problem most likely the signal (trailer) relay.


CONDITION D:
No
brake or signal on either side.

  • Check all fuses.
  • Test the connections to the rear as described below.
  • Brake lights: Disconnect the Pink #8 wire from the trailer relay.  Push on the brake pedal (Ign. on) and measure the voltage or use a test light on the pink wire.  If the wire is dead, the brake light switch may be bad.  Jump the Pink and Violet wires at the brake switch to test.  If the switch is defective, we have improved versions available.
  • Test the signal lights as described above  - (No signal lights on either side.)

Testing the connections from the dash to the bulb
  • If you also have no parking lights at the rear, check the ground to the light and the ground that attaches to the bumper bracket.
  • At the rear bulb socket, unplug both the red and yellow (or green) wires from their sockets, noting their respective locations.  Turn the parking lights on and touch the red wire to the socket that it wasn't in.  If the light is still dead, your bulb is dead , the contact is corroded , or is misaligned.  Remove and replace the bulb (If you have a VOM, you can test the bulb now.)  It may be necessary to remove the whole light assembly to check the socket condition.  If you test it outside the car, don't forget to ground the stud.
  • If the bulb and connection are good, disconnect the pin junction to the rear harness at the left side of the dash.  This is labelled A on early cars, #29 on later ones.  Make sure that all the pins are fully inserted into both blocks.


Testing the signal switch (Requires VOM)

  • Disconnect the B/W/G wire, the B/W wire, and the B/G wire of the switch from the ERA harness.
  • With the signal switch in the left-turn position, make sure that there is continuity (Zero ohms) between the B/W/G wire and the B/W wire.
  • With the signal switch in the rightt-turn position, make sure that there is continuity (Zero ohms) between the B/W/G wire and the B/G wire.

If either of those conditions are not met, the switch is defective.


Testing the front parking light

  • Unplug both the wires  (red and green or yellow) from the parking light corresponding to the dead side.
  • Turn on the parking lights. Touch the harness red wire to the green wire of the parking light.  If the bulb doesn't light, the bulb is bad, the socket isn't making contact, or the ground is bad.  The ground connects at the front of the upper left shock mounting bracket.

Basic Wiring Primer and Troubleshooting Guide
(not finished, but still very useful)