05 Envoy windshield washer pumps not working

[Junfan]

I just got an 05 Envoy last night. I forgot to wash the windshield and today I went to use it and nothing. I checked both front and rear and neither of them spray. My truck is not equipped with the headlight washers.

I checked the washer level and I can see the solution. I then started looking around and noticed that the green taped connector to one of the pumps was not plugged in. I got my volt meter and had it ground and when my wife hit the switch I do not get any voltage. I am assuming I should see something like 5 or 12 volts on this motor? I also see the blue taped pump is plugged in but the rear is not working as I had mentioned.

I did replace the fuses and verified the relays are in place. I am new to these trucks but would love a little guidance. It appears maybe I have a short or bad grounds?

Thanks!

Kevin

 

[IllogicTC]

Sorry that nobody got to this sooner. I'm glad to see you've already at least done some basic troubleshooting. I believe these should show +12V when powered.

Have you had a chance to grab our service manuals? They're available for free and offer all kinds of service information, including full-color diagrams. All in PDF format here if you haven't found them yet.

If it was just one or the other, I might have also suspected the switch but as it's both I'm definitely suspecting wiring. The common point between these two pumps is the ground, G103, which is located on the left side of the radiator support. Trace the black wire from one of them and follow it clear to the end, you may indeed find your culprit there.

 

[Junfan]

Thank you very much. I did find those diagrams so I am going to head to the garage with my laptop and see what I can figure out.

 

[Junfan]

Here is what I just confirmed. I have 12 volts at both fuse locations. I think they were numbers 7 and 9. I had already checked the fuses and replaced them.I then was able to get continuity from both terminals to G103 on the left fender wall. At this point I had my wife hit the stalk button and I could clearly hear the relay and my volt meter spiked around 10 volts and then when back to 0. Same thing happens on the other motor. What I have also figured out from this is that the left motor is for the rear and the right motor is for the front washer.

The only real difference between them is that the one for the front only blips like 5 volts or so then back down to 0.

Possible both motors are bad? I can hear the relay clicking for sure.

 

[BlazingTrails]

It sounds like the tank had dried out and some crud is stuck in the pumps. Have you tried cleaning them out?

 

[IllogicTC]

They may be bad. If something were physically jamming them, I would expect either the fuse to pop or the motor to have continuous draw (with an ammeter, one may note that during initial spin-up amperage is greatly increased, in some motors up to 2x the maximum draw rating. This levels out as the motor gets to nominal velocity). This however is not entirely out of the realm of possibility.

I would suspect that the former owner ran the tank dry, then kept hitting the buttons expecting something to happen and not understanding that they are not operating the Enterprise, and thus the vehicle does not contain replicators.

Removing for further inspection and testing is heavily encouraged before buying replacements, if possible. A good bench test and cleaning and BlazingTrails suggested just to ensure they're indeed toast.

 

[BlazingTrails]

Brushless motors fed thru a relay do not short, if he laid on the switch long enough it might blow a fuse. But if you hit the button and nothing happens your not just going too hold it down for 30-40 sec? Does he have an amp probe? I doubt it......

Also I just remembered the circuit is fed thru the relay on the wiper motor. Are your wipers acting up at all?

 

[IllogicTC]

Brushless motors fed thru a relay do not short, if he laid on the switch long enough it might blow a fuse. But if you hit the button and nothing happens your not just going too hold it down for 30-40 sec? Does he have an amp probe? I doubt it......

Also I just remembered the circuit is fed thru the relay on the wiper motor. Are your wipers acting up at all?

He was rattling off voltage numbers, I would hope it's a multimeter as they're fairly integral to modern vehicle troubleshooting. I don't think the motors would draw terribly much, so a meter with 20A capacity (going off what the rear motor's fuse goes off at, I would suspect it draws less) would be fine.

The fuse feeds the relay and is presented with a ground through the wiper motor's circuitry, and also the other side of the relay which feeds the front wash motor. The wiper motor itself has a separate power supply, not run through a relay (it's controlled entirely on-board the motor assembly's circuitry).

The rear washer also has its own power supply, wired up the same way pre-relay but presented a ground on the control side of the relay by the BCM instead of the wiper motor assembly.

I'm still with double-checking and physical removal for cleaning and inspection as you suggested. I was thinking more along the lines of the washer motors using the fluid as "cooling," sort of like how the fuel pump does, though thinking twice I wouldn't think something under temporary use with lesser draw would require such a function.

 

[BlazingTrails]

I'm wondering if his wipers engage when he hit the washer? I kinda doubt that the wiper motor board is the problem though if the rear is out too. Hopefully it's just clogged motors......

 

[IllogicTC]

If confirmed clogged it may also be worth inspecting the hosing as some of the dirt likely settled throughout those, too. Not sure on a recommended practice, but I have read of people using a blast of air (not a crazy amount) to help clear them out.

 

[Junfan]

Well here is where I am at. I popped both lines on the motors and fluid was flowing easily, I assume the pumps are not clogged. I did remove and look them over and they seem to be just fine. I am not sure but thinking it may be worth pushing a few psi with my compressor through the lines. So what we really have here is two fuses, a relay for the washer motors and it is also tied into the wiper relay?

The wipers seem to act just fine when I hit either button I have not tried just laying on the button and seeing if i have continuous draw. I will do that now.

I feel like I need to look closer at the relay wiring make sure it is working correctly.

 

[IllogicTC]

No. Wipers have NO relay. They're controlled by some circuitry onboard the wiper motor itself.

The front wash has a relay of its own, and the rear wash a relay of its own. These are relays 42 and 38 respectively. There may be other relays with the same model number, you can try swapping and seeing if there's any improvement.

 

[BlazingTrails]

I said the relay board was on the wiper motor dude. And the front washer motor does feed thru the relay on the wiper motor.

 

[Junfan]

Thanks for your help. I just got it fixed. Since I knew I had good relays, hear clicking, and the volt meter looked good I hit advance and got a couple new motors. This solved the problem.

Willing to bet they ran them with nothing in them and burnt them up.

 

[BlazingTrails]

Sweet

 

[IllogicTC]

I said the relay board was on the wiper motor dude. And the front washer motor does feed thru the relay on the wiper motor.

Not according to the diagrams... it's a relay in the underhood block, with the control side grounded via the wiper motor control board. It wouldn't (or shouldn't) take a relay to control another relay. All digital man, acts just like the power button on the radio. The motor itself gets power from the fuse, through the feed side of the relay, direct to the motor and then ground (both are like this).

I'm not trying to one-up you or belittle you. I understand your pedigree in industrial systems and I can dig the experience you have. I'm just going by what's on the paper, in an attempt to have the most accurate information possible presented to the casual forum passer-by.

 

[Junfan]

Maybe replying to this is not appropriate but I figured sharing may help someone else trying to figure this out. I am going to broadly outline a few steps I did to resolve this. Others helped me a ton but having a decent process was the real key for me.

I was driving home from my new purchase, Hells Yea! , and tried to use my washer. It did not work so I shrugged, grinned and assumed it was empty. I got home and found it full. I then started by trying to find a place to talk other Trailblazer/Envoy owners and found this place. Great Find!

Once I posted the first time and got a wire diagram I verified continuity on grounds. That worked I still even took the time to remove the ground, wire brush clean it, chase the treads and reinstall with antiseaze. I am pretty confident they were good after this.

I then moved on to the fuses and relays. I checked straight voltage to the fusebox on the power legs of fuses 7 and 9.

I then started testing each time my wife pressed the buttons by grounding my volt meter and could see clearly that we had 12 volts on both motors.

I then listened to BlazingTrails and iLlogicTC and made sure fluid was going through the motors. Once I know all this I decided motors were the issue. I got a couple installed, filled with fluid and all was good.

My real point of all this is two things. Listen others advice and take the time to work through the learning process.