1995 blazer.
Problem the pump does not spin or spins very very slow.

Has 11.5 to 14 volts at the washer pump harness. Pump motor is new and works perfectly with direct battery power of 12 volts. I check harness for short using multimeter and no fault found. I am at a loss.

 

It could be that you have good power, but the motor has a switch on the ground side controlling it that's bad. I would check the ground wire to make sure there is little resistance with and with out the switch activated.

 

There's a pump out back? After owning my ZR2 for almost 11 years now from buying it brand new, I've never seen a use for a rear wiper.

Let alone a pump.

Could have something to do with that tire blocking the rear view. I don't know...lol

 

I agree i never use the rear wiper i think its because the tire lol

I do use the washer when its muddy or salty in the winter

 

ok, i did check resistence on the power supply wire. So you are saying measure resistence on the ground wire with switch on and off. So should i place ground probe on a body ground and the other probe on the gournd wire in the harness?

 

Just put meter between the ground wire and a good ground, doesn't matter if its a body or chassis ground. Then activate the switch, if you have continuity when you switch it on, then the switch is good. If you don't, or you have high resistance, then I would look into the switch or the ground from the switch.

 

i had very little resistance with the switch both on and off. I did notice that with the wiper motor running the fluid pump wires had a pulst of voltage everytime the wiper ran. The voltage was very slight but every time the wiper went voltage was in the wire. Does the wiper motor have some sort of capacity in it that helps control the washer pump?

 

I know this thread is old but I had the same problem. The pump would turn but only sometimes and it was too slow to push fluid to the back.First I pulled the pump and put jumpers on the posts to check if pump was working. It was good. Them put test light on plug and noticed the light was weak and sometimes didn't come on. Then I took the switch out of the dash and opened it up. There are two small contacts inside. One each for the wiper and the washer. I cleaned both with the end of a screw driver. Works good now.

 

I do use my rear window wiper every now and then, comes in handy when its a light mist out. Had the rear pump go out once, replace it then all the lines started breaking, living here in AZ, rubber and platic(SP) don't last long. But I still have the OEM wiper blade on there and its a 2000.

 

I do use my rear window wiper every now and then, comes in handy when its a light mist out. Had the rear pump go out once, replace it then all the lines started breaking, living here in AZ, rubber and platic(SP) don't last long. But I still have the OEM wiper blade on there and its a 2000.[/quote]

I get snow and road trash on my rear window but have not been able to find the pump for the rear window. I hear it running, but no fluid. The books say either under the hood (as part of front system) or behind the panel where the jack is kept. Where did you find yours as I also have a 2000 with the spare inside. Which means I have to pull the spare if I want to be able to get a decent look inside the compartment. Mine is a 2dr if that makes a difference.