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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

OK, I'm stumped on this one. Just bought a used washer bottle and pump. When I connect the pos and neg terminals on the pump directly to the battery, she spins like a top. When I connect it to the wiring harness, absolutely nothing. Here's some of the troubleshooting I've done:

Battery reads 12.3 V (car not running)
Wiring harness reads 11.5 V when I pull back on the washer stalk to engage the washer pump under *all* of the following conditions:
- pos & neg leads -> volt meter, no pump
- pos lead -> volt meter, volt meter neg to frame, no pump
- pos & leads -> pump, volt meter -> pump
- pos lead -> pump, pump neg to frame, volt meter -> pump

It sure doesn't seem like a grounding problem...but why am I only getting 11.5 V at the wiring harness??? Is it possible that the switch or the relay are going bad? Is it possible that the pump is going bad and just won't run with less than 12 V (which seems weird for a DC motor)?

Any suggestions????
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erstwhile owner of just about every 924 variant ever made

leadfoot · Posted: Sun Oct 10, 2004 5:20 pm Post subject:

clean the brass contacts in the armature contact....
Leadfoot

Sleykin · Posted: Sun Oct 10, 2004 5:32 pm Post subject:

Put a test light on the plug to the pump with the pump disconnected. Bet the light won't light. Then check the positive side of the plug to ground to see if it lights and then check from the battery + to the ground pin on the plug. You need to draw some current to nail this one down.
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Glenn Neff
Medford, OR
87' 924S

Smoothie · Posted: Sun Oct 10, 2004 6:40 pm Post subject:

One common problem area is in the connections at the back of the fuse-relay panel. Activate the washer stalk with one hand and at the same time, reach down and in back of the panel and wiggle the wires with the other hand. If you can get the pump to come to life while doing this, you'll know the problem's there.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

what I don't understand is why I can read 11.5V at the motor, but not get it to turn over. Shouldn't a DC motor with no load still operate, even if at a slower rate??? Or are these motors real picky about 12V?

I'm not sure it's a problem with loose connections, because I get 11.5 V consistently, everytime at the wiring harness. If it were loose connections, wouldn't it be intermittent or fluctuating?

Still puzzlin'
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erstwhile owner of just about every 924 variant ever made

Smoothie · Posted: Sun Oct 10, 2004 7:10 pm Post subject:

You can have close to 12V, but a bad connection that's limiting the amount of current. Think of, say a 30 gauge wire... You can pass 12V through a skinny little 30 gauge wire, but it won't pass much current (amps). Try running something that requires more amps than the wire will carry - the something won't run and the wire will overheat. In the case of a bad connection, the whole wire may not overheat, just the connection. It can continue to show 12V passing on a multimeter while it's passing only a trickle of current that's not enough to run the component, so the bad connection is like a short piece of 30 gauge wire (or 40, 50, 60 gauge - whatever), limiting the current flow.
(It's why Sleykin said to use a test lamp. The test lamp will need current, not just volts, to make it light.)
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

Clean the tubes they may be clogged.
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

Sleykin · Posted: Mon Oct 11, 2004 1:53 am Post subject:

To really open your eyes about the voltage mystery ... take one lead from your multi meter and put it to the + post of the battery and the other lead to someplace on the top of the battery. Unless your battery is brand new and or squeeky clean you will measure voltage there too.
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Glenn Neff
Medford, OR
87' 924S

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Tubes are fine...cleaned them out with compressed air and the flow free all the way thru the nozzles...

Smoothie, thanks for the explanation...makes sense about the current...that's probably what the problem is...now just to track it down...
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erstwhile owner of just about every 924 variant ever made

Smoothie · Posted: Mon Oct 11, 2004 7:30 am Post subject:

The wiring diagrams tell you which connectors and pins are involved. For the washer pump it's "E20" and "C17". That's pin 20 of connector E (E is fifth from the left when looking at the fuse-relay panel in it's installed position) and pin 17 of connector C (third from left). They're designated "A" thru "F" from left to right, installed. You could pull those connectors and look for any signs of oxidation or burning on those pins and wires (then check all the other pins while you're at it). If they look good, the simple act of unplugging-replugging might be enough to renew the connection and bring the pump back to life if that's where the problem is.
Also, the pump's grounded at ground point #5 (frame rail behind the right headlight) - that might need cleaning.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Smoothie...thanks for the tip (I was never too good at reading those diagrams)...diving under the dash to check it out...let you know what I find...

I have cleaned every ground on the car, including #5
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erstwhile owner of just about every 924 variant ever made