87 CV dash light bulb issues

[mcb82gt]

Searched, but couldnt find this problem.

Pulled the cluster to replace some bulbs out. The low fuel, brake and one more on left of cluster didnt illuminate. (all other cluster lights fine). Pulled the bulbs, they are all good, but not illuminating. WTF?

Is it a bad cluster? Contacts were clean, Flex circuit looked fine.

Fuel level gauge doesnt work either. It is balls low "E". ? related Ill start a thread about the sender unit questions soon as well

Thanks guys.

[87GrandMarq]

I had the same problem with my gas gauge when I first got my 87 mgm. It did move a tiny bit when I cycled the key so I suspected the float. Pulled the sender and behold the float was cracked and full of gas. I replaced it and all has been well since.


Sent from my iPhone using Tapatalk

[mcb82gt]

Pulled the sender, float was cracked and full of gas. Also get no resistange change when cycling the float arm. Gauge doesn't move when grounding the sender plug harness with key on.

Should there be voltage on harness plug of sender with key on?

[sly]

The clusters are known for getting small cracks in the traces. These can be fixed by using some of that rear defroster repair conductive epoxy. They also can have corrosion at the connectors and oxidized contacts don't make for good connection. Clean those up and it may fix the issue. Also, check the bulb holders to make sure they're still ok and have good continuity from the contact to the board to the bulb contact.

As for voltage on the plug, With the sender disconnected, one wire should show voltage. I don't remember how much though. The other wire should reference ground when disconnected or look like a resistor to ground. Been a while since I've seen that schematic.

[87gtVIC]

Grab an EVTM and while on a bench you can easily test everything by applying voltages and ground where called for. Then once confirmed all works as should in the cluster you can test on the cars harness. Dont run the vehicle too long with out the cluster installed as the alternator will not charge without cluster installed and working bulb installed into batt idiot light spot.

[mcb82gt]

As for voltage on the plug, With the sender disconnected, one wire should show voltage. I don't remember how much though. The other wire should reference ground when disconnected or look like a resistor to ground. Been a while since I've seen that schematic.

It had no voltage at plug with key on. Is it fused anywhere I could check for a blown fuse?

[sly]

Should be fused in the fuse box under the dash. "Instrument cluster and gauges" is usually the line item in the fuse listing in the manual. No clue which fuse though. Need the car's manual for that.