[dochawk]

I was surprised to be bulled over the other night for not having taillights. (by a very polite and helpful Pima County sheriff).

Indeed no taillights, nor parking lights. I have brake lights, backup lights, and headlights. (But both indicators on the hood show headlights on!)

This time, I have the FSM with me, though!

So in chart 1, p. 8A-110-10 [yes, that's really the page number!], I pull the relay, and pin 3 is hot, but not pin 5 (which the arm from three closes to when activated).

So to the next step, pin 2 is grounded, and pin 1 is open (the probe is in pin 1 in the picture).

So shouldn't pin 1 go hot when the switch is pulled?

I hope I'm wrong, as if I'm right, this is not going to be fun to fid.

At least I have headlights & windshield wipers, and can drive the 420 miles in daylight, but it would be nice to have the extra margin . . .)

\

 

[kc5mhb]

You went straight to the outside fuse box. Most of your fuses that will handle stuff like that will be in the fuse panel in the side of the dash.

 

[dochawk]

The inside fuse is fine; I even measured it.

I'm actually using the FSM diagnostics.

If I'm following things correctly, I'm not getting +12 to the parking light relay coil when I should, whether by switch or automatic sensors

 

[rayrat60]

The inside fuse is fine; I even measured it.

I'm actually using the FSM diagnostics.

If I'm following things correctly, I'm not getting +12 to the parking light relay coil when I should, whether by switch or automatic sensors

I have to ask, is there an aftermarket alarm system installed on your car?

 

[dochawk]

No, but I do have a major grounding problem.

At the moment I have toggle switches instead of fan relay switches because the socket for the primary fan relay isn't grounded well enough to engage, and the other acted up (not clear why yet) during final testing in a Home Depot parking lot. (I'd had enough, and just went in and bought another toggle switch!).

My ECM may be bad, or something else may be the issue--most of the time, I don't have AC or heat.

I'm playing whack-a-mole here, and at the moment the most critical mole is tailings for night driving and they'er apparently depending upon the parking lights (the FSM diagnosis for them says parking has to be fixed before diagnosing).

I also have the latches on molex connectors crumbling just from staring hard; they've gone too brittle to work properly (I need to figure out how to use tie-downs to such them upon reattachment, but somehow without stressing and bending the wires going in).

Naturally, problems lie this come when I'm out of state, rather than being at home where I could jack it up or get other folks I know to peek . . .

 

[dochawk]

err, what's happened to the edit button? I would remove the duplicate pictures, and just add this to the prior post:

I picked up a couple of toggles today, so that I can make a tailight switch if I need to.

 

[kc5mhb]

Yeah you will be playing whack a mole until you get all those ground issues resolved. Electric fans require a couple of things to operate. One comes on immediately when the air conditioner comes on and the other when the temp sending unit at the front of the motor reaches somewhere around 221 degrees or so. What you really need to be looking at is a wiring diagram. You could have a bad headlight switch or a broken wire from the switch to the relay. You need the wiring diagram to figure out which wire (color coded) comes from the relay and back to the switch / fuse so you can test it for continuity. If there is no continuity then the wire is possibly broken somewhere. Mice like to get in these cars and chew up wiring, vacuum lines, etc. and cause headaches for us. Rust at the ring terminals for grounds are another headache. I'm glad my Caddy was a southern car and not from anywhere road salt was used as that is another major issue.

 

[drmenard]

Does your 93 have a ccm in the trunk like the 94-96? I had a bad wire from the CCM that turns on a relay that turns on the taillights. What I did was jumped a hot wire to the relay that turns on the taillights when the key is on. On the 94 I have, the relay was under the dash on the left side of column..

 

[silverfox103]

Don't know if this applies to your 93, but here goes. On 94 and half of 95, B bodies and I'm assuming D bodies had issues with auxiliary battery posts which were made of brass, but they had major melt down issues and had to be changed to copper posts. They caused big time melt downs in the fuse box underneath the hood. If you have any signs of melt downs in that box, I would look at that post. It may not apply to your 93, but worth mentioning. I haven't replaced one for @ 15 years, but could probably dig in a little more if you need info.

good luck

Tom

 

[dochawk]

There is a big metal box at the back of the trunk, but I've narrowed the issues.

According to the FSM, fuse 43 by the driver's door connects to terminal B of connector C400, and then to the lamps themselves.

I had a spool of sprinkler wire, so a few weeks ago, I unwound it, stuck several inches out of the inside, and re-wrapped it, giving me a 50 ft extension. I have alligator clips on the far end red & blue wires.

So I found continuity from fuse to C400//B.

I then turned back under the hoot, and the parking lamp relay (upon which taillights also depend) is not wired the same way as the FSM says it should be! FSM has pin 3 hot, and NC to 4, which is is disconnected. On activation, it says that 3 connects to 5.

But that's not what I have. Pin 4 is always hot. hmm.

And feeding 12v to 5 doesn't give juice to fuse 43. (it should show at the bottom terminal).

I used a pair of ***** to trim a fuse tap from autozone to fit, and plugged it in to the upper pin of 43. Another went into the lower pin of 44 (which I'm not using; it's for the hazards, for which the switch is always on, and will remain so until I find the right thread to add a screw--meaning that lower 44 is effectively always hot).

After a few more careful checks, used an alligator cord to apply juice from 44 to 43, and the taillights came on!

Realizing that I didn't have a way to connect the chopped tap reliably to a wire, then trimmed off enough of a crimp-on male spade connector to fit.

So if I'm not going to make it home by dark, I'll use a piggyback fuse tap in 44, which will let me put a fuse in, and has a wire coming out the other side. that fused connection will attach by 12 or 14 gauge to a toggle, with the other wire from the toggle having a wire to the modified spade connector.

And, naturally, I somehow lost my electrical pliers, and had to take a 20 minute round trip to replace them . . .

 

[stargajzer]

There is a big metal box at the back of the trunk, but I've narrowed the issues.

According to the FSM, fuse 43 by the driver's door connects to terminal B of connector C400, and then to the lamps themselves.

I had a spool of sprinkler wire, so a few weeks ago, I unwound it, stuck several inches out of the inside, and re-wrapped it, giving me a 50 ft extension. I have alligator clips on the far end red & blue wires.

So I found continuity from fuse to C400//B.

I then turned back under the hoot, and the parking lamp relay (upon which taillights also depend) is not wired the same way as the FSM says it should be! FSM has pin 3 hot, and NC to 4, which is is disconnected. On activation, it says that 3 connects to 5.

But that's not what I have. Pin 4 is always hot. hmm.

And feeding 12v to 5 doesn't give juice to fuse 43. (it should show at the bottom terminal).

I used a pair of * to trim a fuse tap from autozone to fit, and plugged it in to the upper pin of 43. Another went into the lower pin of 44 (which I'm not using; it's for the hazards, for which the switch is always on, and will remain so until I find the right thread to add a screw--meaning that lower 44 is effectively always hot).

After a few more careful checks, used an alligator cord to apply juice from 44 to 43, and the taillights came on!

Realizing that I didn't have a way to connect the chopped tap reliably to a wire, then trimmed off enough of a crimp-on male spade connector to fit.

So if I'm not going to make it home by dark, I'll use a piggyback fuse tap in 44, which will let me put a fuse in, and has a wire coming out the other side. that fused connection will attach by 12 or 14 gauge to a toggle, with the other wire from the toggle having a wire to the modified spade connector.

And, naturally, I somehow lost my electrical pliers, and had to take a 20 minute round trip to replace them . . .

Hi,

If your car has EVER had an aftermarket alarm system installed the brown parking lamp wire is cut and crimped to make the connection for alarm flashing lights, if you're not the original owner I would remove the door sill (plastic trim which runs between the door gasket and the carpeting) and look to confirm that the brown wire has not been cut or have a nylon crimp fitting in line because if it does the rear half of the wire traveling to the rear of the car from that point may have fallen out of the crimp fitting or not enough strands to provide sufficient current.

Does the car battery have the original steel battery cable bolts? Or any other type such as weak brass (yellow/golden colored), even if it looks good at first glance may not have strong battery contact or simply poor. Perhaps removing both bolts and inspect the cable ends, these side post connections often oxidize, a simple mix of water and baking soda poured over them (when removed from battery, remove bolts also) will dissolve accumulated white powder oxidation.

I have a 95 DeVille, these cars eventually will experience strange electrical performances with various features which happened to me once my garage queen recently reached 75k miles, contact corrosion begins forming in the exterior fuse bank, one thing which you may rarely see posted here is this. I suggest everyone do this as preventative maintanace.

Purchase a bottle of electrical contact cleaner from home depot and a tube of dielectric silicone grease (bought mine from Amazon), remove the plastic fuse box cover in the engine compartment driver's side, including the small black cover which encloses a bank of relays. Disconnect the positive battery cable, Take a few good photos of the fuse and relay banks using your smartphone, remove all fuses and relays and spray the contact cleaner over all of the fuse & relay sockets, then spray some onto a shop rag or paper towel to wipe the fuse and relay legs (bottom part of fuses and relays), apply a pea sized amount of dielectric silicone grease to each socket, replace all fuses and relays.

Hope that helps