Working on my first 7, an 81 GS, (bought it for my son). Having a problem tracking down some electrical issues.

1. When the parking lamps are on, all work except for the two rear side marker lights. Fuses are all good, there was some corrosion and gunk in the harness connector under the drivers side bin, but I cleaned that all out with contact cleaner and it looks good. Is there a fusible link tucked in there somewhere that I might be missing? I know one bulb is fried, I'll replace it tomorrow but I'm not getting any voltage to either socket. (got dark before I could check the voltage going through the harness connector)

2. I'm not getting any dash illumination, all other dash indicator lights are working, I'm getting voltage to the dimmer switch control , (was at the bone yard the other day and picked up a spare, swapped it and no joy). This one has me concerned because the PO had done a real hatchet job of a stereo install and I think he may have screwed with the ground on this system. It was blowing the tail illum fuse repeatedly until I yanked the stereo.

Any pointers on where to look would be greatly appreciated!

Thanks,

Karl

 

Okay,

Got the rear sidelights working, seems there was just a poor connection to the rear harness. After shoving my voltmeter probes in and out several times along with more contact cleaner they're working fine.

Still having a problem with the dash illumination though. If anyone can illuminate me as to how that system is wired I'd greatly appreciate it!

If anyone knows how I can bypass the dimmer switch that might help eliminate the dash cluster as being a problem?

Karl

 

Hi Karl, and welcome aboard.

First and foremost: Ensure that your son is very comfortable driving the sev, and that all of it's safety devices (belts, steering, brakes and ESPECIALLY tires) are functioning properly. Make sure your son drives responsibly, and never never gets behind the wheel after drinking. Just take every precaution you can to keep that kid alive.

Second, wiring diagrams are available for download at: http://www.iluvmyrx7.com./1st_gen_manuals.htm

I'm chasing the same issue (dash lights), but I haven't gone deep into it yet.

Hope this helps,

Jamie

 

Thanks Jaime,

I have a wiring diagram for the 85 that I found here,

http://www.wankel.net/%7Ekrwright/ca...85_manual.html

but there are some differences, and I haven't really looked at a schematic diagram in about 27 years or so (10th grade electrronics class )

Karl Jr is the most responsible kid I ever knew so I'm not worried about him driving the 7, and as soon as I get the all the electronics working again, next project is brakes, bushings, steering and suspension. Probably get it up on a lift this week. Being on the safe side , he hasn't even driven it until I get all that taken care of.

Thanks again,

Karl

 

I'm bumming,

Does anyone know where the ground from the instrument cluster is located? As far as I can tell the ground wire is the black wire coming off of the combination meter connector on the back of the intrument panel (I could be wrong, long time since I read any schematics, and I wasn't all that good with them then!). What I need to know is where does this system ground to the frame? From the combination meter it goes into the wiring harness and from there, I have know idea.

Also, I'm noticing quite a bit of surface rust under the dash. Is this an indication of electrolysis, (I know that it is generally associated with solutions like sea water), but could a short or bad ground cuase this type of corrosion under the dash? I don't see any evidence of water leaking through the dash or windshield, that's why I'm thinking current.

I tested the cluster itself and the lights do work when using a seperate power supply, just won't work when installed.

Thanks,

Karl

 

Yes, It is for everything else in the car. CHECK, and DOUBLE CHECK the grounds around the passenger side headlight motor. Before I fixed them, I fried the circut board on the back of my cluster, and lucky me, I'm good at soldering. I swear to god that was the cause, and after I fixed that, It fixed ALL of the wiring on my car. HTH.

 

Okay, grounds near passenger side headlight motor is on the worklist for tomorrow. Any other places anybody has had problems with? Unfortunately I think it maybe some of the wiring the PO messed with, he really had one screwed up stereo install.

 

If the wheel on your dimmer switch rotates more than 180*, then the fine wires in the switch are broken and the switch is toast. When they fail, there is usually no backlighting in the cluster. I have had one though, that failed on high illumination.

 

Whilst hunting the same identical problem, i traced the wires to to a green with pink stripe wire that goes from the dimmer switch to behind the radio. Where it's supposed to go after that is beyond me. It's been a butchery behind there, and I wish I could get a look at another 1st gen to see where everything goes. Double check your dimmer. You should have 1 power in and 2 grounds with the lights off. When you turn on the parking light switch, one of the grounds (not the black) should turn to power. I've pulled my cluster out, and all the lights have ground, but nothings feeding them power. It's frustrating as hell. There are no fuses blown, no fusible links blown. The only thing I can account for it is the person that went nuts behind the radio. If you pull out the little cubby hole thing, all the wiring runs behind that. The connecter plugged into the back of the cubby hole is for speakers. I have absolutely no idea why mazda decided to brainstorm up that little piece of infinite wisdom. Anyways, let me know what you find out.

 

Yea, I traced a bunch of problems back to the cubby hole area wiring that relates to the factory radio. Check this out... the PO was having some wiring problems, so he cut off the little plug thing on the back of the cubby hole (no idea what that is about) and used adhesive to reattach it.... so he could plug the adapter back into it UPSIDE DOWN As soon as I got that straightened out I had headlight on chimes which were not evident before.

It had to be done on purpose, I could see the hacksaw marks on the back of the little cubby tray. After he screwed that all up he went to a auto stereo repair place that hardwired power directly from the battery using like 8 guage wire, and not to be outdone, after the pro install he went and added on to it creating more bad grounds and crap. It was interesting pulling that stuff out, they must have been really stoned when they installed.

Hopefully I'll get it all figured out soon

 

plan on pulling my dash sometime in the next 2 days or so, ill take you routing/connector pic's (82 gsl), should help you find your grounds and anything else that might be damaged/cut off