83 944 fuse box shenanegans

[cauzomb]

Thought I'd throw this out there for folks to have a look at.. The burnt pin is plug D pin 3, "the blue plug on the back of the fuse box" The pin is connected straight to the battery mains via plug H bus bars and feeds power out to the headlight switch terminal 30..

I'm wondering if that would be caused by someone upgrading the headlights, without using a remote relay/harness.

I found mention of the H4's needing a harness while searching through the forums, with possible electrical meltdowns after a while due to not using a remote relay harness.. I'm building a harness using scrapyard parts and wires that I tested to be good.. going to use new headlight plugs and new crimp connectors, heavy duty fused power wires from either the battery or the alternator, up to a pair of weather resistant relays etc.. I have another post here with the schematic that I made, along with pics of the wires and relays that I'm gonna use.

I had other shorts to ground but the worst damage to the fuse box looked to be mostly in the headlight circuits, the headlight switch was also melted inside.

[Slam]

Ah, the blue plug. Every single one of these I've seen in early cars has been burned, even if only slightly. Ubiquitous.

[cauzomb]

strange.. It is the headlight switch though.. Even the VW that I got the spare parts from had some heated looking terminals in the blue plug... but it was far from the burned plug that mine had. Check out how the plug looked.

[944 Ecology]

Let me guess, H4 lenses with high wattage bulbs.

[cauzomb]

correct.. previous owner installed H4's no remote harness.

[cauzomb]

They also did this with the fuse panel and harness wiring..

[smokin_944]

Now that is nasty!!

[Gordon Rankin]

I ran all 3 of my 924s with the H-4s with 80/100s with no remote harness and no problems whatsoever!

[89-944NA]

That's one nasty mess you got there partner. Gotta run those remote relays with the higher wattage bulbs or you risk that meltdown mess

[Gordon Rankin]

Eventually, I'd like to put H-4's back in my car..Are the remote relays expensive or complicated?

[89-944NA]

not really, a pretty straight forward and easy job, and cost is minimal...relays are about 5 or 6 bucks i believe, and you just need the one

[89-944NA]

That last picture looks like to PO glued the bottom of a cough syrup cup over the relay. THAT'S SCARY, REALLY REALLY SCARY

[HondaDustR]

Actually, you need two relays. One each for low and high beams. Running 80W bulbs with no relay is stupid. The original design isn't really sufficient even for standard bulbs. My swich eventually melted before upgrading to a relay harness. If you saw the little tiny contacts inside the switch, you would know why it's unreliable carrying full headlight current. Besides safety and reliability, it massively increases lighting performance even with regular sealed beams. I had a 1.8v drop between the battery and the bulb before, and the relay harness with 10 guage leads supplied from the alternator lug had a drop of only 0.15v. It's literally night and day difference, as halogens lose a good bit of light output with relatively small voltage drops. I wish I did it sooner...the $90 for the ticket because it crapped out at the worst possible time would have been nice to keep.

[Rjackel944]

WOW. that last picture looks a little too familiar..my car's a wiring nightmare itself, with random wires hanging everywhere too.

good luck

[cauzomb]

Originally Posted by 89-944NA

That last picture looks like to PO glued the bottom of a cough syrup cup over the relay. THAT'S SCARY, REALLY REALLY SCARY

Actually, it's an epoxy mixing cup that I glued on, over the completely melted, now repaired relay that was originally hanging down off the fresh air blower socket, have another relay to replace it, but I wanted to see how long it would last this way.

It's internal contacts and fuse holder hot side were exposed, dangling behind the fuse box, and part of the hot wire on the back of it "somehow" shorting to ground

[89-944NA]

Sure am glad they moved the fuse box under the hood on the later cars, cleans everything up under the dash, and makes life easier to work on the wiring in the box. Good Luck

[cauzomb]

Originally Posted by Rjackel944

WOW. that last picture looks a little too familiar..my car's a wiring nightmare itself, with random wires hanging everywhere too.

good luck

Thanks, it's nearly finished

I got all but the remote relay harness and some tucking away/tying up of some wires to do yet and I need to check the foglight harness up front, as well as repair the chaffed cooling fan wires.

Looks like the fan wires hit the fan at some point in time and wore through the plastic wire loom and partially into one of the ground wires on the passenger side.

Got most of the stuff for the wire repairs and remote headlight relay from VW's at the wrecking yard.

I still need to get some locking crimp on connectors for the relay sockets. My new headlight plugs arrived recently, now I have almost all the parts to build the remote relay.


headlight harness parts more headlight harness parts

I'll try to take pics of the before/after headlight performance for the low beams, I don't want to turn on the high's without the relay's, considering all the repairs I've done, I don't want to melt any more wires or headlight switches.

Thought of using a foglight remote relay. Since I don't use them very often and now that they are connected correctly inside the car, I don't think I'll need them on a remote relay. Power out to the foglights is provided through the main fuse box, I'm not sure if my foglight bulbs are standard power rating or not, if they are upgraded, or over powered, I can probly just put in lower power rating bulbs and be done with it. The foglights were NOT connected through the factory harness under the bumper via the white/yellow wires.

Those wires were connected to the fuse box, on the wrong G terminal.. Probly why the foglights were powered via PO's "custom" wiring nonsense.

There was a 1,0mm blue wire leading from the foglight switch, all the way out to the fogs in series. This wire was literally wrapped around the moving part of the steering columb under the dash!! Why people do this kind of thing is beyond me..

The foglight switch wire that was connected to the hot wire leading out to the fogs was a Gray with Blue stripe 0,5mm wire on terminal 58b of the foglight switch. This wire is supposed to be power to center console guage lamps, foglight switch lamp, rear defogger switch lamp and somehow tied into the seatbelt warning relay circuit.

The wiring guide shows that the foglight switch has two lamps, but it looks like mine only has one, little green lens on the top side of the rocker, when the switch is in the on position it lights up.. Maybe there is another one, like on the headlight switch illumination that lights the front icon of the switch? Didn't notice one there, if there is, it's probly burnt out due to the over current draw from the fogs.

As hondaDustR has mentioned, the factory wiring is barely able to cope with the current draw of the stock headlamps, and due to all the extra connections, there is quite alot of voltage drop before the headlights connection.. This gets worse with age as the ground terminals become corroded and more resistant to current flow.

The improvement in power to the stock headlights with the use of remote relays is very noticeable, and the lack of current load on the internal fusebox/lighting circuits will prevent the headlight switch/high low selector switch and fuse box plugs from melting, as well as you can build the remote relay harness to suite your headlamp current draw needs..

Another poster has pointed out that the burnt blue plug is a common issue..

The pin that burnt on my blue plug was D3; it's connected to the red wire that sends full constant current from batt+ to the headlight rocker switch, if the switch is in middle/on position, current from D3 goes out to all the parking/running lights, the foglight switch, the emergency flasher switch and the headlight lifting motor wiper tracks that control the lifting motor up/down position.. regardless of ignition key position, power goes to those items...

Power from D3 to the headlight lifting motor is returned back into the fuse box via the wiper traces on the lifting motor via plug D pin 4.

This circuit is tied into the 2,5mm black with yellow wire on the ignition switch, as well as the high/low beam switch on the steering columb which selects the high and low beams via a 1.5mm white or yellow wire, with internal fuse box connections that ultimately go through the headlamp fuses on the fuse box, then out to the headlamps through the plugs on the back of the fuse panel. Each connection/plug between the power source and headlamp bulb increases the resistance..

What it looks like to me is that when you overcurrent the circuits with higher power headlamps, D3 wire and the headlamp switch may act as another current path for the headlights to draw more power, through a gagle of different connections, the headlight lifting motor wiper tracks, dimmer switch, ignition switch 2,5mm black with yellow etc.

Putting the headlamps on a remote relay removes the extra current draw from the current paths in all of those connections as well as eliminates the resistance due to the extra plugs/connections between the power source and the bulb..

[cauzomb]

Still some work to do in the dash harness and behind the DME but the fuse panel is done.
First pic was on the 17th, putting things up to the fuse box and chasing wires down, finding more issues to fix, I had it all back in and running/driving a couple days ago, but not finished with all the wiring, just wanted to test things out and give it a shake down to keep an eye on my cooling fans/temp guage.




Second pic is from this afternoon, after I got a box from Ideola that contained a fuse box wire cover, plastic fuse cover, and a couple other parts "Thank you Dan"

[Gordon Rankin]

Did you do all this work without pulling the dash itself?

[Rjackel944]

Wanna come do mine? lol