HELP - Wiring harness for power operated window tailgate
 

I posted this same thread on the '73 - '87 message boards, but thought I'd post here too in case there was someone here with experience on this subject:

I am upgrading the manual roll up window to a power operated window on the tailgate on my '75 Blazer. Has anyone had experience doing this that can provide assistance on the correct wiring for this application?

The power operated '91 tailgate has two pigtails:

A. One harness has a Light blue wire and a white wire.

B. The other harness has an orange with black stripe wire and a black wire.

I am assuming one is for power to the window (but don't know which of the two), the other to a defroster maybe?

Second question, did later model Blazers include a push button switch to raise and lower the window from the drivers seat, or were they opened strictly from the key insert on the tailgate?

I am installing a Painless wiring harness, so power to the tailgate is available.

Thanks in advance for any helpful information on this subject!

the later model blazers do have a switch to operate window from drivers seat. i have a 90 and its on the left side of the ashtray. if it ever stops raining here i'll pull the tailgate panel and check the wiring.

I can't remember exactly, which one is which, but I think the orange/black and black wires go to the switch in teh tailgate that was operated by the key. The others run to the front to the switch by the ashtray. If I remember correctly the rear window motor does not work using reversing polarity like a regular window motor. the motor actually grounds through the tailgate and 12v on one wire makes it go up and 12v on the other makes it go down.

muddbugg72 and bagged 74 thanks for the help. I've yet to sort it all out.

Let me ask this, it appears there may be a lock in the latch as wires go to the drivers side latch in the tailgate. Dos this ring a bell? Can the tailgate be opened with the window up? and can the late model latches have a power lock on them that prevents the handle from unleashing the latch when pulled?

As I ran the window up and down with the drill, I noticed the latch would not operate with the window in a partially up position.

Also, since I do not have the correct key, I'm un able to test the motor using a 'turn of the key' after putting a hot to any of the wires to test. I also don't want to risk burning or shorting out the motor.

Does anyone have a wiring diagram out of a maintenance manual for these gates?

By the way, the gate installed perfectly into the truck. Amazing the fit and finish since a '91 gate going into a '75 truck.

I think the window has to be all the way down for the gate to open. I also believe that when functioning properly, the window will not operate unless the gate is closed.( I think this is what the switch on the latch is for) not sure, but maybe this will help.

78 was the first year this option was ava....
79...the next year the wiring changed quite a bit...for the better in my opinion...

There is a molded plug that comes out of the firewall....then the harness runs the lentgh of the frame to the tailgate....when i had my fuel tank out 2 years back doing my TBI swap i remember the harness being extremely brittle...ie: jacket falling off the wire itself.....and this makes for our friend resistance to grow up and be really happy....lol. Most of the terminals outside are all series 56 delphi units...par for the course from the mid sixties up...

If i had a old harness i could build a new one using the old one as a template...but both the spare K5's i have out back have nothing left as far as wiring for the tailgate. But basically in a nutshell i really recommend building a new harness so you won't have to complain about the slow rear window....

DW

Doug, I'm installing a Painless wiring harness, with all brand new wiring. I currently have only one 'ignition' hot spare cable that I ran to the back of the truck. Painless originally intended this cable for the electric fuel pump which I do not have. At any rate, what I'm trying to figure out is how to wire the two pigtails that are on the tailgate.

A. One harness has a Light blue wire and a white wire.

B. The other harness has an orange with black stripe wire and a black wire.

I am looking for the proper hot and ground connections for these two harnesses. If necessary, I can always run another hot to the back of the truck or as I have spares in the terminal block in the firewall or split the one I have.

Do you know how these two tailgate harness' are supposed to be wired?

Yes...i can answer that question. Just a moment...have to run down the stairs to the garage and retrieve my 91 wiring book...

Ok....
Black is ground....

Orange w/black stripe is your batt hot (constant)....fuse panel to the tail gate key switch...so you can operate the tail gate glass with a key from the outside without ign switch being turned on.

Light Blue is your "DOWN" from the dash switch....which runs thru the deadman switch on the left rear latch...then to the motor..

Tan/Wht is your "UP" from the dash switch

Pink wire is batt hot (Switched)...from fuse block to the dash switch...


Light / Blue @ Tan/ White will have a splice somewhere in the tailgate harness to split between the regulator motor and the key switch...

I recommend using a high quality DVOM like a Fluke to ohm all circuits to make sure one leg of the circuit doesn't have to high of resistance.... 0.1/3 tenths of an ohm are considered normal values...start getting over that....especially 2 and 3 ohms you will suffer from the slow window curse.

Some tailgate parts were not born to last...glass seals seem to last 3 to 4 years....course i lived in az back then but...
The deadman switch is made by Indak...and they still make alot of switches in the diesel buisness where i work...but they have a tendancy to be the weak link in the whole deal....currently mine is deleted from the system. The terminals at that harness are series 56 on the older units...can't say what a newer unit uses as i've never had one that new open. Cables also seem to wear out after a few years...once the cable sheath comes away from the ends you will have the squeeky rear window...cured by a flick of the dash switch only to return minutes later...

If the latches in your tailgate are worn...so are the strikers...and saying this they should be considered a mated pair..don't change one without the other...

Hope this helps out a bit.

Doug W.

Doug, this is just terrific information. I think with this level of detail I can wire up and test the gate this weekend. I'll let you know how it goes.

I don't have a fancy ohm meter, only one that tells me I have continuity, so I'll have to judge the resistance of the existing wires the old fashioned way, by how fast the window travels.

Regarding the latches on the tailgate, I can not tell you how sweet they installed and latched to the existing strikers. The drivers latch was a little low, so it rubbed slightly on the portion of the striker that starts to widen out, but a little dremel action and it is smooth and tight!

Again, so helpful!

I'll be ringing you up again when I start wiring the Auxiliary battery. Since youre a chalet guy and an electrical genius, I'll need your help with the wiring and relay installation.

Thanks, Greg.

I fell into wiring years back at the first freightliner dealership i worked at and was pretty successful so it all got lumped into my lap...i do all the big three engines and the new Mercedes MB900...(Cat-Cummins-Detroit)....autoshift trannies (Meritor @ Eaton)....plus our product line of trucks and then some.

Relays aren't to bad to wire
Terminal 30 is Power in...
87A is power out to said consumer
85-86...one is ground and the other is what is used to triger the relay...allways forget exactly which is what till i get involved trouble shooting something.

Also having a bad ebay habit really helped...i have all the helm manuals from 73 to 99....and allmost all the wiring books...lol.

Plus i enjoy this board as CK5 can get a little boring with the same questions being asked all the time...



DW

Doug, you lost me on that last dialogue regarding the auxiliary battery. I'll need to hook up with you in more detail on that subject when I'm ready to install.

Meanwhile, I'm having a little trouble with my dash wiring. I just posted this on the '73-'87 message boards and wanted to see if you could help:

Can someone provide some input on how to correctly wire a new Painless wiring harness with a '75 dash that has an amp meter vs. a volt meter.

Currently, the Painless wiring diagrams call for the following:

#935 Pink/Black - source
Black - ground

These two wires provide an ignition switched continuous 12v hot with ground. It's blowing the 10amp dash fuse and warming up the printed circuit pretty good too.

This will provide volts which would work for a volt meter, but not an amp meter.

Can anyone help with the correct wiring for an amp meter?
Thank you, Greg.

Doug, I've figured out the problem I was having with the ammeter. It should be 12 volt power in and out in series with the battery hot, and not grounded. That would explain the smoke from the printed circuit when trying to ground. From all I've read ammeters are not recommended for High Output alternators, so I'm switching to a voltmeter.

Now, back to the tailgate. I've got a power window switch that has a total of 5 pins sticking out the back.

Can you help with the wiring of this switch?

Row 1: There is one pin in a row by itself.

Row 2: There are two pins sideby side, with one pin twice as long as the other.

Row 3: There are two pins side by side, same height.

Thank you, Greg.

Here's a pic of the back side of the switch.

The diagram shows row "B" your ign power...can't remember the other two as far as up and down off the top of my head...working to much lately....

Do member the diagram only using one terminal of each row A-B-C....

Do you have the correct GM connector to hook up to the switch? If so it will be marked a-b-c-d-e-f....fromthere i can tell you what goes where.

DW

What a great thread... I'm getting ready to start the same thing, my question is do I have to use a factory switch which I don't have, or can I use just a toggle switch maybye someone could find one @ mcmaster.com that will work for me.

alf, I would reccomend using oem switches, or at least a toggle switch that returns to netrual when released. I believe a fuse will blow or wires overheat if the window was to be in the fully down position with continuous hot to the motor. Replacement power window switches are available in the 'help' section of the auto store.

76 Chalet, regarding the wiring harness for the windows here's what I found:

1. GM has discontinued the wiring harness for power windows. My local dealer had only a passenger side power window harness for $129. I'm not even sure how much of the harness that included, didn't bother to go look, sooo.....

2. Off to the salvage yard, where I scored big. Driver side and passenger side combination wiring harness for window and power lock, and an extra window harness for the power tailgate... $30.

This wiring harness has a removable clip at the power window unit, and another at the power lock. It has the female receiver that will fit in the pins that are shown in the pic above. And finally continues through the door. If at the salvage yard, it's very easy to remove the entire harness without cutting any wires. All that's needed is a phillips to remove the door panel and old window switches.

I'll post pics of the harness tomorrow.

The harness i am hunting now is a 90-91 Burb...K5...power window harness with the optional 2 year only power mirrors...would allmost give my left testy for it so i can reproduce a set for my 76 Chalet that is going to get rebuilt from the ground up with some modern changes...

Speaking of chalet...if all goes well tomorrow i will have the new motor set in place....woohoo!

DW

76Chalet, I sent you a PM with this same request for information on the power window harness termination, but just in case you didn't get it, I posted it here too. This was posted on the message board, but didn't get a response. I was hoping you, or someone here could help me sort this out:

HELP- Wiring harness for power door window/locks - terminal connections?


I have installed a later model OEM power window set up in my '75 Blazer doors. Wiring harness is also GM from the same year as the power window operators.

All is installed nicely, including switches and wiring harness is terminated.

The other end of the wiring harness has two clips that terminate under the dash near the main fuse panel.

One is a grey clip that has two female terminals on it:
1 terminal - 2 blue wires.
1 terminal - 2 black with white stripe wires.

The other is a black clip that has three female terminals on it:
1 terminal - 1 orange with black stripe wire.
1 terminal - 2 grey wires.
1 terminal - 2 tan wires.

Can someone tell me the source for each of the wires mentioned below so I can terminate the clips into the fuse panel?

I assume the orange with black stripe is continuous hot? The others I am clueless. Also, if you know what size fuse will be required inline with these wires that will operate the motors, but still protect the system.

Thanks in advance for any help on terminating these wires.
Greg.