Imperial dash lights out

[patrick66]

On the '66, I recently replaced all of the bulbs that backlight the cluster, as all but one were out. replaced them one by one. The beautiful dash was looking good. Got to the last light (next to the clock), replaced that, and all of the lights that backlight the dash went out. The turn signal indicators and the high-beam light still work. All of the gauges work, as before. Fuses are all good, that I can tell. Replaced three with new fuses with the same result. It is far easier to replace the bulbs with the dashpad out, believe it or not! So, that is the only thing from keeping me from reassembling the dash!

Any ideas???

 

[Big_John]

The dash dimmer switches contacts get dirty. Twist that up and down a bit.

 

[Polara_500]

Did you take that last one you changed back out, just in case? You know, back up one step first?

 

[patrick66]

Yeah, and the others remained out. What I'm afraid of is possibly having shorted out that circuit board somehow. I've checked the rheostat in the headlight switch. It was working full-range before the lamps went tits-up.

 

[OneEyed]

Don't the bulbs all ground themselves when they're plugged into their socket? Maybe your lost that ground? Either way, I'd start with a multimeter or test light

 

[Davea Lux]

Don't the bulbs all ground themselves when they're plugged into their socket? Maybe your lost that ground? Either way, I'd start with a multimeter or test light

You either do not have power to the dash lights or they do not have a ground. My guess is that you may have fractured one of the circuit pathways with the new bulb install. As mentioned above, try a test light to the hot side of one of the sockets, if you have power to the test light, most likely you have a grounding issue. Grab a multi meter and run a continuity check from the ground terminal of one of the bulbs. (Run Ground to a known good ground, it should show minimal resistance) If you get an open reading, the ground fault is confirmed. You may have to pull the cluster and locate the fault within the circuit pathway. You can do this by checking power and ground to each socket. When you lose one or the other you have located where the faulty socket is.

Dave

 

[patrick66]

Cool. I'll give that a shot this weekend. Thanks!