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A friend of ours just bought a 1998 Ford Expedition.

Not working:

  • Hazard flashers
  • Turn signals
  • Brake lights

However, head and tail lights both work when they're turned on.

We tested the brake light switch, there's continuity when the brake is pressed. The plug that plugs into the switch has ~12v current. However, in the fuse box neither the 15A or 5A fuses that are supposed to deal with brake lights/turn signals are getting any kind of voltage. There is also no voltage at the brake lights (which was expected, given that they just changed the bulbs).

Also looked through the fuse boxes in the engine compartment as well as under the dash, nothing was obviously blown.

The person they bought it from removed the stereo... is it possible that is causing the problem? If not, what are the other possible causes?

  • You said the tail lights work, but you measured no voltage on them, is that what you mean? Do the front flashers work? – HandyHowie Feb 25 '16 at 21:30
  • If it helps there is an electrical system troubleshooting manual available for $24 USD. Not sure what its contents are. Wiring diagrams could be useful for you. – Jason C Feb 25 '16 at 21:33
  • sounds like it needs a new multifunction switch. Does the high mount brake light work? – Ben Feb 25 '16 at 21:53
  • If they had a custom stereo installed, and they didn't use a nice wiring harness (ie. they just hacked up the wires) there's really no telling what they may have cut to get power to the radio. How does that area look? – JPhi1618 Feb 25 '16 at 22:03
  • @HandyHowie - the tail lights work - the brake lights do not (two different wires, two different bulbs) – Wayne Werner Feb 26 '16 at 14:05
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On the Expedition the hazard, lower brake lights, and turn signals all route through the multi-function switch.

Gain access to the multi-function switch connector and back probe the light green wire while pressing the brakes.

Does it have power? If it yes back probe the light green/orange and orange/light blue wires while pressing the brakes.

Does it have power? If yes there's a continuity issues between the multi function switch and rear lights. If no it needs a new multi-function switch.

protected by Community Mar 7 at 21:02

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