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Notchback To Fastback Tail Light Wiring - At Wits End by whadeduck
Started on: 07-18-2009 03:50 PM
Replies: 20
Last post by: fierohoho on 08-31-2009 11:45 PM
whadeduck
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Report this Post07-18-2009 03:50 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
Working on War Hammer trying to get the brake lights to work so my friend Paul can carry it back up to Wyotech with him next weekend and use it as his DD. Found this thread //www.fiero.nl/forum/A...020319-2-011713.html and tried to remove terminal J9 so I could switch it. After six hours, several small screwdrivers, connector removal tools and paperclips, terminal J9 still remains in place. I can not get the thing separated from the connector. I also can't find the terminals C7 and H8 on C500 that The Ogre was talking about. Can someone please help? Pictures and/or diagrams would be greatly appreciated.

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Report this Post07-18-2009 05:02 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
Here's the pin out for C500 (this is from a notchback '86):



To remove the pins, you must first remove a white (might be blue) plastic pin-locking mechanism that looks like a comb out of the side of C500. All you can see of it is the white plastic back part of the "comb". Use a small screw driver to pry it out. Be careful and pry it up evenly at several places a bit at a time or else it will break. Then you can remove the electrical pins by using a bobby pin and pushing up on the little metal tang of the pin shown in the picture below, while gently tugging on the wire from behind.



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whadeduck
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Report this Post07-18-2009 05:27 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
That should help on getting the terminal outta there. Thanks. Now on to which one where. The car is an '88 coupe that has a fastback conversion. One not well done in the wiring dept. So J9 on the rear light harness supposedly activates the brake lights. In the write up from The Ogre, he says to move that connection to C7 on the connector to get it to work. I may be reading the diagram wrong, but it doesn't look like there even is a C7 spot. So I'm still a little confused about which wire I'm supposed to cut and which one gets switched to where.

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Report this Post07-18-2009 07:08 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
1988 you say eh? Well you shoulda said so before! Here's the '88 pinout for C500.



Now on to your dilemma. You never said whether the engine half of the wire loom you are trying to connect up is from a fastback or a notchback. It makes a difference. I re-read TheOgre's post embedded in your first post and it only works if you have the fastback tail light harness. He also made a mistake when he referred to C7, he meant G7.

Here's what you have to do if you have a notchback rear wiring harness and want to convert it to work the fastback tail lights:

- remove the white wire and pin from slot H8 of the engine half of C500 (the other end of this wire jumps back to pin G7;
- cut off the pin from the white wire that used to be in slot H8 and strip the insulation back 1/4 inch;
- cut off the wires leading to pins H7 (yellow) and J8 (dk green) from the engine half of C500 leaving the pins in C500 and leaving a little wire to spare as you will use these again for the turn signals;
-splice together the yellow and dark green wires coming from the lights (not the short ends still connected to C500) using one end of a butt connector, then splice them to the end of the white wire you stripped that is still in slot G7 to the other end of the butt connector;
-that completes your stop and rear marker light circuit. You will have two brake lights and rear marker lights per side.

Next move on to your new turn signal circuit:

- use or buy some single filament bulbs and sockets for the turn lights, as many as you want but stock is two per side;
- run a common ground wire from all the socket grounds to any convenient ground point;
-run one power wire for the right hand turn signals sockets and one power wire for the left hand sockets to C500;
- splice the new RH power wire from the sockets to the dark green wire you cut off from C500 J8;
- splice the new LH power wire from the sockets to the yellow wire you cut off from C500 H7.

And you're done.
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whadeduck
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Report this Post07-18-2009 07:46 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
The rear harness is from a fastback. We tried using the existing wiring from the notchback only to get nowhere. So when Paul and I switched fastback pieces, we figured it was a good time to swap the notchback rear harness for the fastback one he found earlier. I think I may have it working. I depinned J9, found a suitable terminal, and plugged the blue wires going back to the tail lights into G7. So far so good I think. I have to let the car's battery charge for a bit. Then I'll retest everything. Does what I just did sound about right?

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Report this Post07-18-2009 08:31 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
Interesting you say blue wires. According to the '88 service manual, the wires leading back to the brake lights are white, but it makes sense that they're the same color as the high level stop light circuit (ie blue).
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whadeduck
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Report this Post07-18-2009 09:46 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
Got the brake lights to work. But now, when I use the turn signals or 4-ways, the brake lights and turn signals flash alternately as well as the "PONTIAC" light. WTF?

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Report this Post07-19-2009 10:36 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
If you explain all of the wires you moved, and to where, I can help, because I'm not certain right now which method you used.
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whadeduck
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Report this Post07-19-2009 04:25 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
I moved J9 to G7 on the light harness. That was all I did.

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Report this Post07-19-2009 04:36 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
According to the service manual, there wasn't supposed to be a wire in J9 in the first place. If your Pontiac emblem is flashing, I'd say you mistook G8 for G7 since G8 is the lead for emblem. Remember the connectors halves are mirror images of each other so it's easy to get screwed up which hole to put pins in.

According to the book, you shouldn't have had to do anything since there should've already been a white (or blue) wire in the slot G7 of the light harness.
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whadeduck
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Report this Post07-19-2009 06:45 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
I think I'm gonna haveta really just sit down and study the diagrams. The car is/was an '88 notchback. But there's no telling what year fastback the tail light harness came out of. Thanks for all of your help Blooz.

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[This message has been edited by whadeduck (edited 07-19-2009).]

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Report this Post07-19-2009 11:21 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
The taillight harnesses for fastbacks should all be the same regardless of year.
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Report this Post07-20-2009 02:16 AM Click Here to See the Profile for jscott1Send a Private Message to jscott1Direct Link to This Post
 
quote
Originally posted by Bloozberry:

The taillight harnesses for fastbacks should all be the same regardless of year.


Not true....

first of all the 88s don't have the blower motor.

There have been mixed results between harness of different years going into cars of different years. The Helms says it's plug and play but there are too many counter examples that say it is not.

When I did my 88 coupe I used an 87 fastback harness and I had no brake lights. I had to do the fix described above.

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whadeduck
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Report this Post07-26-2009 09:14 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
This is getting rediculous. The car has developed a personality all it's own now. Tonight, I took a few minutes and checked some things. Wanted to get the parking lights and "PONTIAC" lights working. So I checked the appropriate terminals on C500 and made sure they lined up with the appropriate terminals on the tail light harness. Everything lined up and should have worked. So I plugged the harness together and, not only did I not get any lights, but now the freakin' radiator fan comes on.

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Report this Post07-26-2009 11:31 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryDirect Link to This Post
Your best option at this point may be to match wire colors between connector halves rather than pin outs.
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whadeduck
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Report this Post08-15-2009 03:31 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
Here's an update on the lack of progress on the car. After working on it for a total of about another ten frustrating hours, I've got absolutely nothing more accomplished. De-pinned the stuff and tried everything out, and everything seems to be in the right place. But it still doesn't work. Break lights work, PONTIAC lights are on as long as the keys are in the ignition. But when you cut the turn signal on, the front turn signals work properly but the back don't. In fact, instead of the back turn signals working, it's the brake lights that flash. They're not even hooked up to the turn signal circuit. =0 I just got off the phone with Paul, the car's owner, and he filled me in a little on the car that may help. The car has a 3800SC Series I conversion done by ACE. To do the VATS bypass when the car was done, they used either a Cadillac or Buick steering column. So maybe that has something to do with all of this.

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whadeduck
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Report this Post08-16-2009 08:09 PM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
Well, as an update, I finally bit the bullet on this one. Checked one of the sockets for ground by taking off the rear bumper and support, cutting one of the ground wires and finding a good ground. Ureka! It's the grounds. However, because of a stripped stud in the rear roof section, I can't get to the ground. So I've unwrapped all of the wires and I'm re-doing everything by removing some of the wires and grounding everything to the chassis. Wow, didn't know there was so much wasted wire in even a small harness like the tail lights. I think the turn signals were trying to ground out through the brake lights causing the weirdness I was getting earlier. But I have half of the car done and working so far and I should be able to get the other half done soon. For anyone reading this, if you do a natchback/fastback conversion, make sure when you change your tail light harness, that your lights all work. Then bolt down the rear clip.

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Whade' "The Duck Formerly Known As Wade" Duck
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[This message has been edited by whadeduck (edited 08-16-2009).]

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Report this Post08-16-2009 11:37 PM Click Here to See the Profile for pontiackid86Click Here to Email pontiackid86Send a Private Message to pontiackid86Direct Link to This Post
easyist way to do it is splice it. you have to connect j9 to somthing i just forget what you have to tap it into. its been about a year since i did a fast back swap.
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whadeduck
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Report this Post08-17-2009 12:30 AM Click Here to See the Profile for whadeduckClick Here to Email whadeduckSend a Private Message to whadeduckDirect Link to This Post
But what most of my problem seems to have been the whole time was that the main ground for the harness wasn't grounded well. But with the rear roof panel in place, it's just about impossible to get to. So, despite it taking some work and time, I think this is probably a pretty good way to guarantee that I get good ground on all of the lights. It's working so far anyway.

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Report this Post08-31-2009 10:12 PM Click Here to See the Profile for CamelClick Here to visit Camel's HomePageClick Here to Email CamelSend a Private Message to CamelDirect Link to This Post
In my 88 notchback convert, I used a 87 GT taillight harness, I had to swap G7 to J9 or vise versa (if you look on your notchback harness youll see the one thats switched), also I had to ground that large bulky ground to the frame that went to the 87s trunk fan setup, if I didnt I would get random lights working and some dim and weird stuff.
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Report this Post08-31-2009 11:45 PM Click Here to See the Profile for fierohohoClick Here to Email fierohohoSend a Private Message to fierohohoDirect Link to This Post
This may be a little late but the thread below has a couple pics at the bottom of the thread on how to remove wires from C500.

Steve

//www.fiero.nl/forum/Forum2/HTML/098863.html
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