Rear window wiring question

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shmukster

shmukster

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Working on a 55 erar window yesterday and shorted the blue wire in the tailgate to ground. yes this is the hot wire that runs from the dash all the way to the junction block in the tailgate. Now I have no power. No fuses are blown- can someone tell me if there is a fuse or some other protection between the battery and the circuit breaker in trhe window circuit? Thanks, Gary S
 
what year? I wanna say there is no extra pro in between the bat and the breaker, but they changed the wiring there a bit over the years. check breaker with ohm meter, sometimes they take a while to reset, sometimes they just die. is there power at one side of the breaker at least? if not, then you'll need to chase further forward of the breaker to find the prollem.
 
Success

Well, went home yesterday determined to see what happened. Couldn't see the circuit breaker from underneath the dash so pulled the instrument cluster, made the CB accessible. Checked it for continuity and it was OK. re-attached the battery terminal (!!!) and checked for voltage- had it on both sides. Looking good. Tried the window switch, didn't work. Hmmmmmmmmmm reinstalled the instrument cluster, turned on the ignition and tried the switch. Window works! Doesn't work unless the key is in the "ON" position.

I cut open a sacrificial 73 harness from which I had salvaged some parts to see how the light blue wire is routed. With what I have left of the behind the dash harness I could see the blue wire coming in from an end I cut off, to the circuit breaker and back out to the relay. I can only assume on my truck that the source of current that energizes the relay is in ignition mode only. So now my window works fine from the dash switch. The tailgate switch doesn't work at all- the keys I have don't turn it. I have some extra switches but none with a key! I remember on my white 72 piggy back when I wheeled it, I just mounted a SPDT switch riggt through the tailgate shell, it was a waterproof switch that I got from work. Worked trouble-free for years.

And why, you ask, did I have to fix my regular wiring when I had my tailgate window working with a remote? Well I had some developmental trouble (ha ha ha). The relays that I used that get energized by the remote latched in and I was unable to de-energize them in time to keep the window from jamming hard in either up or down positions. Since I had bypassed the circuit breaker (but was fuse protected) I didn't like that setup. I still have the wiring and relays in place, they're wired in parallel to the original wiring. I need to find some other relay setup to make this work- and I will do it, especially now that the weather is starting to warm up and alot of the snow gone.

Anyway it's story with a happy (for now!) ending. gary
 
I think the tailgate gets special wiring i.e. it usually doesn't go through the ignition [EDIT: wrong; there are two paths for power to the tailgate motor. In this message I'm missing one.]. The idea being that when the key in the tailgate is used to move the window there does not need to be a key in the ignition as well. I think. [EDIT: yes but there is also the ignition-to-dash-switch ciruit]
 
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On the 78's the ignition switch has to be on to operate the window from the dash switch - just like Gary said. The main switch in the tailgate is always hot.

Glad you got the window working
 
I just had to redo part of my 78 tailgate. If the colors are the same, the solid blue wire should always be hot, and that feeds power to the keyed switch on the back. The dash switch will route power through the black/blue or white/blue wire depending on position only when the key is on. I think it shares a junction (pre-fuse IIRC) off the white/blue alternator wire at the fuse box, but my engine harness is so hacked I have no idea what actually goes where anymore. Maybe there's a fuse/fusible link between the battery and the solid blue wire's beginning?
 
Ming89FJ62 said:
On the 78's the ignition switch has to be on to operate the window from the dash switch - just like Gary said. The main switch in the tailgate is always hot.
Click to expand...

onemanarmy said:
other years may be different, but on my 77 the ignition has to be 'ON' for the dash switch to work. The rear switch on the door will work at all times with the key.
Click to expand...

My 76 is the same, key has to be on for the switch on the dash to work. Rear switch switch is always hot.
 
On my 69 the tailgate power shares a source that powers the ignition switch. The tailgate wiring is always hot, however there is a circuit breaker before the tailgate window switches. The breaker is located in the dash on the steering column, very hard to get to. The main power wire looks like 10 ga and the owners manual indicates the wire is "light purple".
 
I can say that while my 73 tailgate works from the dash switch only with the key in the "on" position, and the wire that goes to the switch on the tailgate door is always hot, the schematics I have in my older manuals show that both switches should always be hot. Nowhere in these schematics does it show that the current runs through the ignition switch. Hmmmm. The ignition switch is fed, however with the same heavy wire that comes from the alternator and goes to the circuit breaker. I see nowhere, either, that other than the circuit breaker is there any protection in the tailgate window circuit. And (old age here) I don't remember how the window in my 78 worked. I'm just glad my window is working! Gary
 
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