1993 940 Turbo Wagon: DRL & Mis-wired front turn signal sockets
 

I recently added a turn-signal style daytime running lights kit to my 1993 940 Turbo Wagon. (This DRL kit was from www.WebElectric.com)

Upon installation, the DRL kit was not functioning properly. I traced the root cause to the fact that the front turn signal lamp sockets were wired incorrectly. (I think they were like this from the factory.)

On these light sockets, which hold dual filament 1157NA amber bulbs, two terminals were reversed.

The common terminal of these bulbs (the outer metal can) should have been wired as the ground terminal, but instead, on this car, they were wired to receive the +12V blinker signal. Whenever the turn signal filament was lit, it resulted in an elevated Voltage on the bulb's other terminal, which was the dimmer filament for the parking light. That elevated parking light Voltage was confusing the DRL circuitry.

Anyway, I re-wired the turn signal sockets, which fixed the issue. (And... I really love my new DRL kit. The turn signal lamps are very visible.) However I'm curious about whether this turn signal mis-wiring was widespread or if my car was the oddball.

If anyone has a similar vehicle and gets a chance to check their turn signal sockets, I'd appreciate it if you could let me know what you find.


Thanks, Wayne

(Note: When bulbs are mis-wired as mine were, they perform essentially the same as correctly wired bulbs.)