Fog lamp help

[rockfangd]

Hi all. I would like to add Oem fog lamps to my 1997 Deville.

I cannot seem to locate a wiring diagram for them.

I dont think it is prewired for them, at least not to the bulbs.

I want to see if I get them if I can replace the headlight switch and add the option, or if I have to dedicate a circuit for them.

My 01 eldo had them and it was a ice feature, but it seems that if it was not equipped that it was not prewired.

Any info is appreciated. Thank you

[Cadillac Jim]

I would guess that most or all the wires are there. The reason is that the schematic on page 8A-103-0 and -1 shows this:

1. The fog lamp switch, which is a press-on, press-off wide rectangular button beside the headlight knob, grounds a line to the IPM when the fog lights are ON.
2. By implication, the IPM tells the PZM that the fog light switch is on over the network. The PZM then grounds the coil of the fog lamp relay in the engine compartment relay center. Power comes from the 10 Amp IGN 1 Fuse, which powers a lot of little things and will be installed in your car.
3. Power supplied through the 10 Amp FOG FUSE in the engine compartment fuse/relay center is switched by the fog lamp relay and goes to the front fog lamps. A separate line goes to the headlamp switch to turn on the Front Fog Lamps ON Indicator LED.

So, I would check and see if the 10 Amp FOG FUSE is installed, and put in a 10 Amp auto fuse if it is missing. Look for the wires and connectors for the fog lamps to be rolled up and taped to the harness where they break out for the fog lamps. The wires are PPL (hot) and BLK (ground).

You will need to change the headlight dimmer switch with the knob to get the fog light on-off switch with LED indicator.

[rockfangd]

Thank you for posting that.

I have not seen the pigtails but i will look again. If they are hiding they are hiding well.

[Cadillac Jim]

I would look for the fog lamp relay too. Without the option, it is probably not there.

[rockfangd]

So just as I expected there is no relay, not even wired for the lamps, relay or fuse. Which leads me to believe it is not wired from the headlight switch either.

I installed the lamps which was cake. Required no modifications.

I built my own harness which is just like how GM would.

I am going to put in a relay that is negatively activated and put a discrete switch somewhere low in the dash.

All I need to figure out is how to run the switch wire through the firewall to the switch.

Keep in mind I dont like any modifications but if it is not wired for it I improvise as lightly as I can

[rockfangd]

Ok so I have a somewhat update here.

I have the lamps installed and the headlight switch with the option.

I have found that the headlight switch is wired the same with and without the feature.

I also bought the relay and a section of the wiring to it from a donor.

If the relay and pigtails were there this would have been long done already.
I am working on closer details. I will post my results soon.

I drew up a wiring diagram specific for the foglamps and I must say it is ridiculously over complicated.

ground goes to headlight switch, foglamp input

when foglamp switch is on it outputs ground to the IPC

the IPC then outputs via datalink to the PZM at the back of the car to turn on the foglamps

The PZM then outputs from the back of the car all the way to the foglamp relay under the hood.

foglamps turn on.

Then (yes there is more)

The purple wire that is 12v that goes to each foglamp also runs back to the headlight switch to tell the indicator to turn on.

The things I go through to make sure things are done properly. I dont know if I can pull it off. If the wire from the pzm was present I would be all set but I dont think it is there.

Everything at the headlight switch is present and works properly. Guess I will have to pull the back seat to find out

[Cadillac Jim]

If you have a 1997 FSM stop me.

The wire from the headlamp switch is ORN and goes to pin D7 of connector C3 on the IPC.

The wire from the front fog lamps relay is the ORN/WHT wire and it goes to pin C6 of connector C2 on the PZM.

There are rear fog lamps. But, only on the Eldorado/Seville. Funny, I never noticed them. They are an extra bulb in the rear lamp assembly.

The rear fog lamps rela coil is powered by the same 10 Amp IGN 1 fuse. The rear fog lamp relay is in the trunk compartment relay center #1. The relay coil is grounded through a YEL wire connected to pin C7 of connector C2 on the PZM.

The RED wire to the headlight switch, pin H of connector C1, is for the rear fog lamps LED. The LT BLU wire from the headlamp switch signals the IPM through pin C8 of connector C3.

In the rear fog lamp bulb wiring, the connector numbers and feedthrough numbers differ between the Eldorado and the Seville but all are RED wires on circuit number 122.

[rockfangd]

Update 5/16/16.

All done finally.

The foglamps are completely oem .

I ran the wiring like it were prewired. Everything worked on the first try which was very nice.

They are pretty bright.

Anyone interested in doing a job like this I would happily do a writeup on it.

Thanks for the help. If I can find a few minutes of sanity I will share a few pics