Hello

I have a 1970 442 and I am wondering if my dim interior lighting is due to the age of the wiring ( corrosion) or if my dimmer switch is not working correctly. I can barely see the lights on the gauges when the dimmer is on full.
Anyone had this issue and resolved it?

Thanks!

 

I would suggest measuring the voltage at the dash lights to see if there is any voltage drop from the battery level. If yes, your suspicion may be valid.

 

My battery was at 13.05V... Those bulbs should be blinding me...

 

What's the voltage at the 4A INST LPS fuse in the fuse box?

 

Good Question.. Ill check it tomorrow or thurs.. Any other Voltages to check while i'm at the car? ( Unfortunately its not at my residence.)

 

If the voltage at the fuse is approximately the same as at the battery, the problem is downstream from there in the dash harness or the grounds on the other side of the circuit. If the voltage at the fuse is low, check the rheostat in the headlight switch and the connector to the switch as the most likely (but not only) causes. Obviously you then need to check voltage drops at each junction in the circuit. The firewall connector is another likely source of a problem. And also check the terminals at the power stud on the horn relay. I've had corrosion there cause dim lights.

 

Forgot to mention.. The power seat is super slow.. I need to help it to move and the windows are slow as well..

 

Evaluate, clean &/or replace corroded wires, faulty wires, wire ring connectors at the Horn Relay Junction/Distribution block post (the bolt where the positive wires attach).

 

In case you forgot to mention any additional items & you might suspect any form of electrical issue(s), it is VITALLY important you have a solid ground system on your car. Electron flow to all systems begins at the negative (-) battery terminal. Evaluate/Clean corrosion from the negative battery terminal at the battery and importantly at the location where the negative battery cable attaches to the engine block. Use sandpaper, wire brush, etc. so you have solid metal-to-metal contact. There's an additional ground (-) braided strap from the passenger (RH) side from the engine head to the firewall - make sure it's there, make sure both ends are clean - sandpaper/wire brush etc. You need metal-to-metal contact. Anything which impedes electron flow from the negative (-) ground side will increase resistance, limiting voltage.

 

The problems with the power accessories may or may not be related to voltage. Wear in the brushed in the motors for the seat and windows can also cause this, in addition to the need to lubricate the seat and window tracks. Again, start by tracing the voltage drops. The power accessories use a circuit breaker mounted on the firewall, so check voltage there as well.

 

Do you have a decent Volt/Ohm/ meter?
A voltage drop test will pinpoint the drop and is the most efficient troubleshooting method for this problem.

But consider 40-50-60+ year old grounds...all of them.
Before diving into anything and to prevent tail chasing, I'd clean all major grounds in the engine compartment and interior harnesses. Start with the secondary (large) battery wires.
The battery cables can look OK, but have high resistance. Measure the Ohms. Clean both ends of the cables. Look for missing ground straps from the engine to the firewall, frame, or core support.

Then go to the primary (smaller gauge) wires. Such as the horn relay junction. Don't rule out corrosion between the fuses and the fuse cradles in the fuse block or a bad bulkhead connection.

For the interior cabin lights, you'll need to look at the bulb sockets and the roof light bulb cradles, door switches et al. This can be a real rabbit hole, but the drop test is your friend.

What's the alternator output?

Once the grounds have been freshened, now start hunting for the drop(s).

 

That doesn't address what I suggested.

 

Voltage is 12.95V on battery.. At the 4a fuse its 11.14V.... Blah!
Negative pigtail on battery is broken off and is bolted to fender lip near horn relay.. I see that it belongs on radiator core as well...
Horn relay is same voltage as the battery.

 

I'd suggest you have some wiring evaluations to address. Note my suggestion (above) pertaining to the negative (-) ground circuitry. Review all your ground connections.

 

Agreed, as I mentioned, get all the low-hanging fruit taken care of before digging down into the finer details.

I will assume 12.95/13.05 readings are the battery surface charge, not the running voltage.
That's a good surface charge. But we need to know the running voltage to further assist.

With the engine running, put a volt meter on (across) the battery terminals...whats the meter read? This is the alternator system output or the system running voltage.
Now turn on the heater and high beams and read the running battery voltage.