Need help troubleshooting windshield washer pump

[Vidal]

Greetings,

The windshield washer system isn't working in my '84 Carrera cab, but troubling shooting it has been perplexing. Any suggestions are welcome.

Inspecting  the pump while someone is pulling the switch at the stalk on the wheel, there is no fluid flowing, and no signs of any activity from the pump. Checking the connectors at the pump with a voltmeter indicates the switch is working fine and the pump should be getting juice. I therefore suspected the pump needed replacement. However, after taking the pump out I decided to hook it up to a 9V battery- it seems to work just fine! Hooking it back up in the car, and nothing happens.

So, the pump works on a 9V battery, but it's not working when hooked up in the car (yet the connectors have juice). Any suggestions on what's going on? 

Many thanks,

Vidal

[LouZ]

When you checked for voltage at the connector, did you use a voltmeter and test from the +pin to bare metal on the car? If so, try a continuity check from the -pin to a body ground.

[Vidal]

Hi Lou,

Thanks for your input.

I just checked the pump, lines and nozzles by hooking up the pump to a 9V battery, and everthing there is working fine. Washer fluid started spraying with no problems. So, it seems it must be something between the pump and the switch.

Now, I'm not an electrical wizard, and I may not be checking this correctly, so let me detail what I've done to check the electrical.

In doing a continuity check, everthing appears to be working OK. Hooking up the voltmeter to the +connector (i.e., the black cable to the pump) and then to bare metal, I get close to 0 ohms only when I hit the switch. So, there's continuity there when it supposed to, and therefore no short.  Connecting the -connector (i.e., the brown cable to the pump) shows 0 ohms at all times. So that appears to be good too in that it is grounded.

Putting the key in the ignition and looking for voltage, I get nothing when connected to the -connector (brown cable), which is as it should be. When I connect to the +connector (black cable) I get voltage only when I pull the switch. This too therefore appears to be working properly.

So, I believe all the separate components of the system appear to be working in isolation, assuming I'm checking things properly. I'm therefore perplexed as to why it's not working when it's all put together. I must be diagnosing this incorrectly, but don't know what to try next.

Anyone have other ideas?

Vidal