Vanrickman

Hi everyone,

I just swapped out my wiper motor and linkage/transmission, and that did not fix the problem of slow and intermittent operation.

The car is a 2003 a4 b6 avant

Any ideas?

TIA

tenspeed

Check the input voltage.

Vanrickman

Would you know what the voltage range should be?

Regards,

Vanrickman

Has anyone had issues with the wiper switch that could comment.

tenspeed

It should be full battery voltage. 12.5 VDC with the engine off and 14-14.5 VDC with the engine running.

The wipers typically have three parts. The motor, a control module and a switch.

The switch sends a signal to the module. The module sends a pulse to the motor via the low speed or high speed wires. There are another couple of wires attached to a internal switch the returns the motor to the park position. Some Audi models have a service position so there is a another wire that parks the motor at a different (higher) position.

I suspect that you have a problem with the module or wiring. Checking the input voltage to the motor should confirm that. I would use a analog meter to check the voltage so I could see the needle sweep. The voltage should be whatever is in the battery and I would be more concerned with when the pulse is sent to the motor, not how much.

You can also bench test the original motor. The case is typically the ground and the red is slow speed. Keep your fingers clear. I still carry a thirty year old scar from a Caprice linkage.

Vanrickman

Thanks for the reply Tenspeed.

I'm not sure what the low and high trigger voltage should be, Main voltage is there (12+). No visible signs of damage to the harness.

When I connect the voltmeter and test low/high I do get a small amount, but I don't know what the parameters should be. Knowing these trigger voltages would allow me to determine if the switch contacts are faulty, or CPU output is incorrect. I believe B6 and up does not use wiper relay just direct output from CPU...(someone please correct me if i'm wrong).

The reason I question the switch is the problem is intermittent. I already bought a motor I didn't need, I'm not interested in doing the same for the switch too if it is something else that someone has run into before.

I had a carb shop in the 80's, so it's not my first go around. Been wrenching over 35 years.

tenspeed

I think that voltage to the motor should be 12 VDC to both high and low. The motor has multiple poles and the speed is determined by how many poles are energized. I don't remember from my DC Motor Theory classes if more poles equals more speed.

With the rain sensors, intermittent functions and speed control, wiper relays are a thing of the past. With the car being a dozen years old, the next easiest thing to try is cleaning the switch contacts. If you can find a wiring diagram, you can check the output to the CPU.

My first real job was at Rochester Products. I put springs on the idle screws and put the screws in the iron on the two barrel line. Working on and tuning carbs is becoming a lost art.