Indicators and hazard lights


Today, I'm looking at some lighting issues on the Mustang:

  1. Left turn signal light on the bonnet faulty.
  2. Emergency lights/hazard lights don't work.
  3. Replace some blown bulbs on the instrument cluster.

Left turn signal

The mustang has a left and right indicator repeater on the bonnet, point back at the driver. Not really sure what the purpose of them is! The right side light works fine. The left side behaves strangely. It flashes maybe once, then doesn't come on again.

Blew a fuse. Should really disconnect battery before touching anything electrical.

Found the fuse. Fuse block upper fuse. Replaced. Still nothing. Poked around the cables. Got the multimetre on the cables coming from steering column.

Discovered by wiring diagram, that the indicator wires are:

  • Left indicator: white-blue
  • Right indicator: Green-?

This made sense, as I could see both of these wires are split under the dash. I'd guess to make a run to the dashboard telltale indicators and to run through the firewall to the exterior lights. Back under the dash, multimeter reveals power going into steering column but not returning. Then noticed the emergency lights switch was not in its rest position. Damn it, fiddling the switch to release where it has caught itself on the steering column and the indicators are working again!

Emergency lights

Removing the instrument cover was very easy. First, all screws that hold it in place so it's being held in by gravity at the moment. To make a little more room, I loosened the top of the dash by undoing 4 screws at the bottom of the windscreen. The instrument cluster could be pulled out enough at that stage to get a 22mm spanner in behind the speedometer to undo the speedo-cable. Unclip 2 multi-plugs and the plug for the wiper switch and the cluster was free.

This revealed the flasher unit for the emergency lights. Removing the flasher unit, which I already know is faulty, I set about tracing cables by colour and with the multi-meter. A white-red wire runs from the flasher to the steering column. By briefly reconnecting the battery and testing for +12v, I could tell that the circuit was good up to the steering column switch. However, activating the emergency lights switch does not power the turn signal outputs from the column. I can only conclude that the hazard light switch is not working.

This could be a tricky one to fix and it most likely means replacing the entire turn signal/steering cam and removing the steering wheel may need a special wheel puller tool. Link.

Instument cluster lighting

With the instrument cluster out, it's a good chance to replace some bulbs that weren't working as well as have a general look at the wiring/various warning lights. It's a totally lifeless cluster, even when the ignition is on, I guess from lack of features. What I found:

  • Two back light bulbs were blown. Replaced them with very similar alternatives from the local motor factors.
  • All fitted warning lights are working.
  • The cluster features a red "Brake" tell-tale bulb fitted that I have never seen illuminated.
  • There is a red "Belt" light but has no bulb/bulb-holder fitted.

Further Google research on the Brake and Belt lights suggests that they are features of a "deluxe" package evidently not on this car. The brake light would be operated by a switch on the handbrake lever.