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2004 chevy trailblazer_ls
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I have an 04 Trailblazer, and I've had a similar problem: up until two weeks ago, my rear windshield wiper worked 100% of the time. Now, the wiper arm works like it's supposed to be, but the washer fluid doesn't come out when it's supposed to. And when I lifted my tailgate to investigate, there was wiper fluid all on the jamb (where the gate locks into the car) like it had all leaked on there. I'm gonna try and take the plastic stuff off (the interior vinyl stuff) to see what's up next weekend.

Suggestions?
 

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Another rear wiper not working

I have the same issue in that the rear wiper does not work. Didn't try the washer. My hatch electric lock doesn't work either. Both started at the same time and in fact the remote will not function despite a new battery.
 

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2004 gmc
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I have the same issue in that the rear wiper does not work. Didn't try the washer. My hatch electric lock doesn't work either. Both started at the same time and in fact the remote will not function despite a new battery.
The receiver for the remote unlock is the rear liftgate control module, which also controls the other functions you have problems with. It could be that its fuse (#3 in the rear fuse block) has gone, or a wire in the harness going to the rear liftgate module is bad. They often break over time due to flexing near the hinge where the liftgate opens. Check out the wiring hidden by the rubber boot.

If your rear washer pump works, that's entirely controlled by other circuits, and not the rear liftgate module.
 

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2003 chevy trailblazer_lt_ext
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My rear wiper works, the license plate light works and I think the rear defrost works (too warm to really tell) Fuses 3 and 6 under the rear seat are good and the radio stays on until I open the door. My problem is the liftgate or glass will not lock with/without the remote. All other doors lock but on the lifgate I can open with the lever or the glass can open by pushing on the button. Is this the wire harness issue or the liftgate module shot ?

Thanks.
 

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... I can open with the lever or the glass can open by pushing on the button. Is this the wire harness issue or the liftgate module shot ?.
Could be liftgate solenoid or mechanical lever issues as well. I'd remove the liftgate internal cover and just look closely as you use the remote keyfob.
 

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2003 chevy trailblazer_lt_ext
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Could be liftgate solenoid or mechanical lever issues as well. I'd remove the liftgate internal cover and just look closely as you use the remote keyfob.
So once the rear wipers and the plates light are working I can eliminate the LCM, correct? and that means no broken wire in the harness?

I know you said as well but I would like to narrow it down as much as possible, if you can let me know.
 

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So once the rear wipers and the plates light are working I can eliminate the LCM, correct? and that means no broken wire in the harness?
Not quite. The license plate lights are powered by separate wiring used by the marker lights, and don't go near the LGM. The rear wiper working is a good thing, since it means that serial data communication to the module is OK. Also if the defogger wires heat up that's also proof that serial communication is OK.

The LGM still controls the liftgate latch assembly, which has only two wires in its connector. To latch it, the LGM puts ground on one and 12V on the other. To unlatch, it reverses the polarity. So your problem could be in the LGM putting those voltages (from its connector C2, pins 6 & 8) into the short harness that goes to the liftgate latch assembly, or it could be a bad latch assy, or the latch assy could be hung up or need lubrication.

Do you hear any clicking from inside the liftgate when you try to unlock or lock the vehicle?

I don't see any way to proceed at this point other than take the panels off the inside of the liftgate, and poke about with a meter on the latch assy connector. There's a tiny chance that one of the three 12V power feeds to the LGM is broken, but the schematics are not entirely clear on which power feed controls which function of the LGM. There are only three of them, and they are all orange wires, so it's easy to probe.

If you're not comfortable or experienced with electrical troubleshooting with a meter, you should just buy some excellent beer and dangle it as bait to attract a friend who is. :D
 

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2003 chevy trailblazer_lt_ext
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Not quite. The license plate lights are powered by separate wiring used by the marker lights, and don't go near the LGM. The rear wiper working is a good thing, since it means that serial data communication to the module is OK. Also if the defogger wires heat up that's also proof that serial communication is OK.

The LGM still controls the liftgate latch assembly, which has only two wires in its connector. To latch it, the LGM puts ground on one and 12V on the other. To unlatch, it reverses the polarity. So your problem could be in the LGM putting those voltages (from its connector C2, pins 6 & 8) into the short harness that goes to the liftgate latch assembly, or it could be a bad latch assy, or the latch assy could be hung up or need lubrication.

Do you hear any clicking from inside the liftgate when you try to unlock or lock the vehicle?

I don't see any way to proceed at this point other than take the panels off the inside of the liftgate, and poke about with a meter on the latch assy connector. There's a tiny chance that one of the three 12V power feeds to the LGM is broken, but the schematics are not entirely clear on which power feed controls which function of the LGM. There are only three of them, and they are all orange wires, so it's easy to probe.

If you're not comfortable or experienced with electrical troubleshooting with a meter, you should just buy some excellent beer and dangle it as bait to attract a friend who is. :D
I can hear the clicking, I did take off the panel and everything looks well lubricated by the latch assembly. I usually spray and grease them before winter. I will follow up by testing voltages, see what I get and report back.

Thanks.
 

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2003 chevy trailblazer_lt_ext
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Took the panel off and checked all 3 orange wires got 12.7 v. Check continuity on the wires and they were good. So I climbed in and start locking/unlocking with the remote and noticed the switch on top (where the lead is) is try to move a lever of some sort but I couldn't see. I pulled the complete unit off and the arm the switch was trying to move was rusted tight (where arrow is).
Everything is back to normal now, thank you Roadie for the tips.


http://s184.photobucket.com/albums/x157/Menthol_03/?action=view&current=SeizedLatch.jpg
 

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2002 chevy trailblazer_ltz
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Sorry to bring a thread back from the dead, but I am also suffering from rear wiper failure and cannot seem to find the source. I just bought a 2002 LTZ, and the PO said that the rear wiper hadn't worked for awhile.

I have checked fuses #3 & #19 in the rear fuse panel, and they both appear to be good.

I did not see any frayed or broken wires in the loom running through the top of the hatch.

I did find that the hose for the rear washer appeared to have popped loose right near the wiper motor, which may explain why some of the metal clips holding the trim on were rusty. I put that back together and it seems to be spraying properly now.

I noticed a fair amount of corrosion on the wiper shaft, which I cleaned up, but that made no difference.

The motor itself looked to be in OK shape, and I have 12V on the orange wire in the wiper motor harness, but the green wire (pin E I think) is always at ground. Vehicle on/off, wiper control on/off makes no difference here.

Since my keyless entry works and I think my defroster does as well (it gets 12V when the defrost setting is on) I don't think the problem is with the LGM.

Any thoughts?
 

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2004 gmc
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Rear circuit breaker #9 brings 12V to the rear wiper motor, (for future reference) but you don't have that problem if your orange wire has 12V. Check A (black) to be a good ground. The dark green wire is a PWM signal from the LGM, so if you command high speed wiper action, that wire should read 5-10V on a meter set to the DC scale, and perhaps the same on a meter set to AC volts.

If the control wire isn't getting any PWM square waves, then perhaps the speed control switch up front isn't getting read by the BCM. Pull the switch from the dash, and check the white wire (pin A) for a 12V reference signal, and the output gray (Pin E) will have a voltage that varies according to the position of the switch. The switch is full of discrete resistors like a potentiometer with a jumpy output.
 

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2002 chevy trailblazer_ltz
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I have 12V on the white wire. The voltage on the gray wire varies depending on the knob position as follows:

0 - 1.6V
1 - 2V
2 - 2.4V
3 - 2.8V

As an aside, I looked at the rear fuse panel again, and I don't have anything in position #9.
 

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2004 gmc
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And dark green at the rear wiper motor is always around 0 volts? Check the same wire on connector C2 pin 3 at the LGM. You did the right thing to check the existence of serial communication to the LGM, so that can't be it. Sorry about the circuit breaker misdirection - I didn't check the 2002 schematic, and assumed they didn't change the design there before my 2004.
 

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Yeah, the green wire was always 0V. Also, if I wasn't clear earlier, the black wire does show as ground.

I'll check the pin at the LGM tomorrow, it's unfortunately too cold out right now. Maybe I can also figure out why my rear speakers suddenly went dead. . .
 

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Well. . .I'm rocking some pretty strange voltages here. Measuring pin 3 on the middle connector from the LGM shows ground no matter what setting I have the wiper on. I know that this pin corresponds to the green wire that goes to the wiper motor because I did a continuity test on both ends of the connector to verify I had the right wire.

Now the really strange part is that if I measure pin E on the wiper motor with the wiper motor connector plugged in, I see almost 12V (11.8 to be exact) on that pin. Even if the connector from the LGM is not plugged in, there is 12V there. Could something have happened to the board on the wiper motor internally, sending 12V into the LGM and frying that pin? Maybe the rear washer line that was loose earlier caused a short?

On the plus side, I replaced my rear speakers and they work again.
 

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Rear wiper and defroster

I seem to have a similar problem with my 05 TB. my rear wiper and defroster do not work. and when i open my hatch it continuously clicks like it is locking. My rear wiper fluid still works, and my key fob works most of the time. What could be the problem? I do not want to take it to the dealership. Hoping I can figure it out myself.
 

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2004 chevy
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Just fixed my INOP rear wiper. The culprit was a broken +12V power wire from the 15A circuit breaker in the rear fuse box to the wiper motor. It broke right in the flex joint at the top of the rear hatch.

Two 3M heat shrink butt connectors, 5" of wire, and about 10 minutes later and it was operational again!

Thanks for the suggestion Bill!
 

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2002 chevy trailblazer_ltz
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Lucky. I ended up having to buy a new wiper motor, but only after finally breaking down and paying the dealer to use their Tech II to determine whether the LGM was bad. I did manage to find a used one for a decent price, so at least there's that.
 

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2002 chevy trailblazer_ls
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I have a 2002 TB and my rear wiper will not run, either.

- washer pump will run
- arm does not move after pump runs
- I have 12 VDC on the Orange wire measured in reference to the Black wire
- keyless entry works
- radio stays on when key turned off
- no visible frayed wires in harness across rear gate hinge area
- can hear "click" from gate area when turn dash switch from "0" to "1" and then back again

Any ideas?
 
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