Electrical issues Continued - no power to the ballast resistor

[Keith R.]

I am perplexed. In checking all the electric functions after hooking up the battery for the first time, I found that the windshield wiper motor would not turn on. It draws power from the inboard ballast resistor terminal which in turn is powered by a brown wire running directly from the ignition switch. I tried jumping the ignition switch terminals and the motor engaged for a split second then stopped. I inserted two mini screwdrivers in the brown wire and red wire connection terminals and verified power across this connection. Still no power at the ballast resistor. I managed to stretch an ohm meter wire from the terminal of the brown wire at the resistor to where it terminates in the connection at the rear of the ignition switch. It was quite a stretch but presuming that the meter terminals were making good contact then I must have an open circuit in this brand new harness which seems far fetched. Does anyone have any idea of what is causing this and what the fix might be? I'm thinking that I am going to have to abandon the brown wire, open up the harness tape and run a new dedicated wire to the resistor from the ignition switch.

[Mark E.]

Re: Electrical issues Continued - no power to the ballast resistor

To clarify-

- power to ignition switch input (red)
- power to ignition switch output (brown)
- no power at ballast input (other end of brown wire)
- no continuity between ends of brown wire.
- before the continuity test, you applied power to the brown lead at the ignition switch and the wiper motor responded for a moment.

Right?

One possibility is the wiper motor has a short to ground. So when you applied power to the brown wire, it powered the motor, but the load caused a huge current draw which fried the brown wire in a matter of moments.

Verify by separately testing the wiper motor in a controlled way which won't cause more damage to the harness.

Another possibility is a weak battery or poor battery connection, either of which can cause erratic problems. This doesn't explain the open brown wire, but maybe that test was a false negative. Verify by checking for a fully charged battery and full battery voltage at the switch.

Or, as you mentioned, maybe a defective harness from the get go.

Is this circuit fused or have fusible link?

[Edward J.]

Re: Electrical issues Continued - no power to the ballast resistor

Keith, the brown must be open. that wire runs from ign.switch to ballast what else can it be. Maybe the crimped end at the ign. switch or ballast was not stripped back properly before it was crimped??

[Keith R.]

Re: Electrical issues Continued - no power to the ballast resistor

Thanks very much Mark. Your restatement of the situation is exactly right. I will try bench checking the wiper motor to see if that is the issue. And, no there is no fusible link or circuit breaker on this car but I will double-check the fuses although none were blown previously. It's hard to believe that it is a bad wire though.

To clarify-

- power to ignition switch input (red)
- power to ignition switch output (brown)
- no power at ballast input (other end of brown wire)
- no continuity between ends of brown wire.
- before the continuity test, you applied power to the brown lead at the ignition switch and the wiper motor responded for a moment.

Right?

One possibility is the wiper motor has a short to ground. So when you applied power to the brown wire, it powered the motor, but the load caused a huge current draw which fried the brown wire in a matter of moments.

Verify by separately testing the wiper motor in a controlled way which won't cause more damage to the harness.

Another possibility is a weak battery or poor battery connection, either of which can cause erratic problems. This doesn't explain the open brown wire, but maybe that test was a false negative. Verify by checking for a fully charged battery and full battery voltage at the switch.

Or, as you mentioned, maybe a defective harness from the get go.

Is this circuit fused or have fusible link?

[Keith R.]

Re: Electrical issues Continued - no power to the ballast resistor

Thanks Edward. If indeed an open circuit then the question arises, where might it be open? If not at the ballast resistor end (which is clearly visible) then perhaps at the ignition terminal. I'd have to cut the harness tape that's wrapped around it and then examine that end. The rest of the wire is wrapped within the harness and has got to be intact as there are no pinch points under the dash.

Keith, the brown must be open. that wire runs from ign.switch to ballast what else can it be. Maybe the crimped end at the ign. switch or ballast was not stripped back properly before it was crimped??

[Keith R.]

Re: Electrical issues Continued - no power to the ballast resistor

Pulled the wiper motor and it performs perfectly on the bench. Tested the voltage at the brown (which conjoins with the 18G pink) terminal and it reads 12.48 volts. No voltage at the terminal at the ballast resistor end. I am thinking that it is a bad terminal connection at the ignition switch as the U-shaped terminal at the ballast resistor end looks good.

[Edward J.]

Re: Electrical issues Continued - no power to the ballast resistor

Keith, that sound like a good idea, maybe the wire at switch is the problem.

[Edward B.]

Re: Electrical issues Continued - no power to the ballast resistor

Go with your original idea and connect a new wire from the ignition switch to the ballast resistor. If everything works the fault is in the old wire, if it doesn't perhaps the fault lies in the ignition switch.

[Keith R.]

Re: Electrical issues Continued - no power to the ballast resistor

In order to bring the thread to conclusion, what I found was that the terminal from the ignition switch to the ballast resistor had the lead wire disconnected which was surprising for a new wiring harness. In any case, a little soldering did the trick and the engine fired right up.

[Mark E.]

Re: Electrical issues Continued - no power to the ballast resistor

Keith,

Thanks for posting the resolution. I wish all OPs did so we can better learn from the thread.

[Keith R.]

Re: Electrical issues Continued - no power to the ballast resistor

I agree Mark. If one starts a thread, one owes it to post the resolution so that it goes full circle.

Keith,

Thanks for posting the resolution. I wish all OPs did so we can better learn from the thread.