1979 1.6 dasher electrical issues

[rjkuljis]

I am having issues with my dasher electrical. It is a 79 with the 1.6 diesel. The issues I am having are likely related in that the electric controlling the radio, the idiot lights, the coolant gauge and seatbelt buzzer, as well as the head lights, and glow plug light kick on and off intermittently. It started that the radio would kick on and off, which I assumed was related to the battery being low as it seemed the alternator was not charging the battery. I then noticed that one of the main grounds coming off the batter that grounds on the battery holder was broken , so fixed that. Not sure if that fixed the alternator problem or not, but the next thing I noticed was that the coolant temp gauge stopped working . I tried to troubleshoot that with no luck, but in the process the other electrical issues started. So while I was trying to figure out the coolant gauge issue, the other issues started, The headlights worked, and then didn't, and then did, also the radio, etc. Then there was some smoke under the dash, I could not see where it was coming from.

the fuse panel is in very good shape, this car has never had leaks, and there is no corrosion. It has had a short in the oil warning light which has kept that light on in the past.. I am going to start there.

ANy advice is much appreciated!

[TylerDurden]

Smoke under the dash can't be good.

First, I'd take the alternator to a shop for testing. If it lost ground while running, the regulator may be shot and pumping higher voltage into your system.

After resolving the alternator, I'd hunt down the source of the smoke. I wouldn't want to energize the system until I found what is likely a dead short or a blown component from overvoltage.

Then I'd ensure all the grounds are in good nick... particularly engine to chassis, chassis to battery.

[Fatmobile]

If you find a positive voltage on a ground wire,... that's bad.

[vwtyp133]

As indicated above, an intermittent ground can allow voltage surges that are problematic to certain devices within the electrical system. The headlight switch can become intermittent, then totally dysfunctional due to a shorted lead, higher-powered bulbs (BTDT!), or just wearing out/becoming sloppy internally. Obviously when the headlamp switch overheats, the instrument panel lighting rheostat can become fried as well. The ground problem(s) you mentioned can definitely trash the solid state voltage regulator (p/n 171 919 303) for the panel's instruments, showing as intermittent or illogical readings. Even if you don't have any water leakage issues around the windshield, moisture can condense on cold metal parts, eventually helping corrosion to form on under-dashboard ground connectors. Solution is to clean them all (while battery is disconnected) with medium-fine sandpaper or a stiff metal-bristled brush.

My '79-'81 Dashers haven't, but many of the VW Rabbits of that era did have recurring problems with ground lead corrosion at (all of?) the external lighting. Adding a pair of relays to power the headlamps' high & low beam circuits not only provides better lighting (even with standard factory bulbs!), but can also greatly extend the life of the headlight switch.

[rjkuljis]

after testing the alternator and making all the ground connections clean and solid I figured out that the positive terminal was hitting arching on the hood becuause this battery is a little bit tall for the vehicle and the terminal for the positive cable was not seated all the way down on the post!!! I am sure this was part of the problem to begin with! I lowered the terminal as far down on the post as I could and put a piece of rubber hose over the terminal for added protection. The way I first noticed is that everything was running good and as soon as I closed the hood I got a bunch of smoke as the ground wire plastic was burned away! I opened the hood again right away and figured out what was going on. Now it seems to run okay except I am still having the fuel and coolant gauges stop working. I tested the voltage stabilizer and that looks good. I did notice the circuit board has a broken circuit for the positve circuit for the clock. Would this effect the other gauges?

[vwtyp133]

Could be. Trace the circuits on the flex panel, or check the connections in your Bentley manual's wiring diagrams to see if the gauges are dependent on the clock's connector for 12V+ power. An alternative is to check the fuel gauge & temp gauges' supply voltage(s) with a multimeter. IIRC the factory clock's power is through a nut-on-stud arrangement, while the fuel & temp gauges are just clipped to the flex connector panel.

[Fatmobile]

You might try checking the voltage at the temp gauge sensor, with the wire disconnected.
To see if the voltage is getting to it.
I can't remember what the voltage from the regulator is supposed to be,.. 10 volts? You should see all of that at the sensor with it unplugged.