1975 Delta 88 the left lowbeam is dim, the left turn signal light is always on when running and the turn signals don't work. However, the hazard lights work if you hold the switch in, but the switch will not stay on without being held in place. I replaced the headlight with no luck. Any suggestions???

Tim

 

Yes.

You have a bad ground, likely in the signal light, but perhaps also in the headlight.

Disassemble and clean all terminals. I would also remove the connectors to the headlight themselves from their plastic plug and clean them, and clean the signal light sockets.

You also have a broken signal light switch.

Welcome to ClassicOlds.

- Eric

 

This applies not only to the connectors, but also to the ground wire where is bolts to the core support or fender. There should be a black wire (or several) that terminate in a ring terminal held by a sheet metal screw.

 

When ever I deal with issues like this as I reassemble I use dielectric grease on all the connections.

 

Also, the radiator support which serves as the ground path for the front lights must be tied to the battery (-) post. Small extra lead originally did this; new cables often do not get installed right.

You can always ck for a faulty ground by reading voltage from the Device Using Power [DUP] to the battery (-) terminal. After the power leaves the headlight for example, via the black wire, it is supposed to have an easy path back to battery minus. Therefore, the voltage at the headlight ground wire with respect to the battery minus post should be zero. They should be at the same voltage, due to being connected together with the car's sheetmetal and some wires- no voltage drop along that path. If there is a crusty connection, or NO connection due to rust, missing wire, etc., then the power will get thru and out of the headlight... but not back to the battery, to varying degrees from "some" voltage drop from a poor connection = dim light... to "no connection" = full voltage drop = Device Under Power does not operate.

So, if you put your red lead on the DUP's exit [ground] wire, and the black lead on the battery minus post, you should get zero volts, or close to it- 0.1 maybe. Note that the DUP must be turned on and using power. Current must be flowing or attempting to flow.

If the voltmeter reads more than a little drop from the DUP's exit wire to the battery minus post, then the electrical path is not proper, and needs to be fixed. You can also ck voltage drop acrosss any part of the path- DUP to local ground part [headlight to radiator support in this case], radiator support to battery minus, etc. That can isolate the problem area.


If y'all have not done this yet, try it.
It is amazing.
Crusty terminals or contacts?

Get a cup of vinegar, microwave it hot
add table salt. A lot. At least some.

Dip your terminals/ headlight tangs/ whatever. Can brush it on probably. Takes ~10s to clean to bright copper or brass.

here are grungy brown pennies after 10sec - it does the SAME THING to your electrical terminals

Rinse electrical contacts in Baking soda water, blow dry, spray contact cleaner if desired, coat with dielectric grease. Ta da.