Headlights Not Working

[RHUGGETT]

I have a 93 class A Rockwood Driftwood motorhome on a 92 Chevrolet chassis.

The headlights work for the daytime running lights, and the light switch will turn on the parking lights, but when I flip the light switch to the headlight position, there are neither headlights or parking lights.

I replaced the light switch with no improvement. The wiring on the switch looks very suspect to me, but I don't know.

Can anyone tell me where each of the colored wires should be secured on the switch contacts?

Can anyone tell me if there are relays for these headlights or where they may be located?

Does anyone know where I might be able to obtain a wiring diagram for the headlights?

I would appreciate any help you can give me.

[desertdeals69]

I would start tracing the wiring from the headlights back toward the switch. If there is a relay, you will run into it before the switch. Check the switch for power output, pull out one notch and one terminal is hot, pull out another notch and two terminal are hot. If you have current on the terminal that is hot in the second switch position, follow that wire to the headlights or relay. Its possible if it has a relay it may be bad or have a blown fuse. You should have current to the park/running lights in both outer switch positions.

[dickandlois]

rhuggett,

Welcome to the FMCA Forum!

Where to look for some information for P32/42 CHASSIS:

Ordering Information

Electrical diagrams are available from Chevrolet and GMC through service publications.

They have contracted the following companies to handle the ordering and shipping of the manuals.

Helm Inc.

P.O. Box 07130

Detroit, Michigan 48207

1 (313) 865-5000 for information and inquiries

1 (800) 782-4356 for credit card orders

General Chassis information link.

http://www.offroadtoybox.com/RV/P-Chassis-AlignmentProcess.pdf

Additional chassis information link.

http://gmupfitter.com/files/media/photo/177/1999_LD_P3242Chassis.PDF

link for.

92 Electrical Diagrams & Diagnosis Manual for Lt. Duty FWD Control Chassis, Value Van, & Motorhome Chassis by Chevrolet & GMC Truck (92_WireTruck )

Listed price $29.95

http://www.books4cars.com/listings.php?findmake=Chevrolet&model=Motorhome&type=%

Hope this helps get some useful information on the chassis circuits.

Rich.

[huffypuff]

I have a 93 class A Rockwood Driftwood motorhome on a 92 Chevrolet chassis.

The headlights work for the daytime running lights, and the light switch will turn on the parking lights, but when I flip the light switch to the headlight position, there are neither headlights or parking lights.

I replaced the light switch with no improvement. The wiring on the switch looks very suspect to me, but I don't know.

Can anyone tell me where each of the colored wires should be secured on the switch contacts?

Can anyone tell me if there are relays for these headlights or where they may be located?

Does anyone know where I might be able to obtain a wiring diagram for the headlights?

I would appreciate any help you can give me.

You say the wiring looks very suspect to you. Do you see any burnt marks on the connectors or wiring there? The reason why I ask is many models during the year of your coach is that the switch carried the load of headlights right through it. It is very common for both the switch and wire terminal block to burn up. The fix for that is a new switch and terminal block pigtail.

[hermanmullins]

rhuggett,

Welcome to the Forum.

Do you have a smart wheel Steering Wheel? If so contact tech support at vipwheels.com. I had the same problem and it turned out to be the Vehicle Improvement Product control box.

Herman

[RHUGGETT]

You say the wiring looks very suspect to you. Do you see any burnt marks on the connectors or wiring there? The reason why I ask is many models during the year of your coach is that the switch carried the load of headlights right through it. It is very common for both the switch and wire terminal block to burn up. The fix for that is a new switch and terminal block pigtail.

I had an electrical service company repair a short circuit in the parking lights 2 years ago and they said at that time that I should replace the head light switch, but they didn't have one in stock. They solved the short circuit and ordered a new switch for me.

When this problem came up, I went to install the switch, and I noticed that a couple of the wires near the switch looked like they had overheated as there was a few areas where the insulation had melted a bit. I cut out these damaged bits and joined on some new pieces of wire. I replaced the switch, but it made no difference.

This switch is a direct replacement for the old switch. It is a rocker type switch that has 6 terminals on the rear. There are 3 terminals on the left and 3 terminals on the right. I did a thorough test with my ohmmeter and there was no connection between any of the terminals on the left side and the terminals on the right side. It was just like there were two switches in one. If a hot wire is hooked up to the center terminal on the left set of terminals, and the switch is rocked down, then there is a connection with the upper terminal on the left side. If the rocker switch is rocked up to the top, then there is a connection to the lower terminal on the left side. There is no connection to any of the terminals on the right side. The same connections are on the right side, but there are no connections between the left and right sides.

There is only one hot power wire connected to the center terminal on the left side, and nothing to the center terminal on the right side. when the switch is pushed down for the parking lights, there are wires secured to both of the upper terminals with a jumper wire connecting them and then another jumper going to the variable switch for the dash lights. I don't know why they used both of the upper terminal since there is no power on the right side. They could have just bundled them together onto the left terminal.

All the parking lights work in this situation. When the switch is rocked up for the headlights, there are no headlights turned on and the parking lights are also off. Although the light do not light up, there is 12 volts showing at the lower left terminal (as there should be).

Again, there are wires connected to both of the lower terminals. Another puzzle here is that there is a low voltage of 8 volts showing on the lower right terminal and its wire even though there is no power supplied to it's center terminal, there must be some feedback from somewhere.

All these wires look to be too light to be powering the headlights directly. I don't know if the wires were messed up when they repaired the short in the parking lights, but something just does not seem to be right. When we are camping, we usually stop for the day by 3 o'clock, so I don't think that we ever drove when the headlights were required. But a couple of weeks ago, I did drive much later and I then found out that the lights didn't work when I needed them. I guess I will have to try and trace the wires from the switch and/or the headlights to try and find the problems.

Thanks for your help.

[huffypuff]

DPDT On-On

Six terminals.

This is how I'm understanding the switch you mention works. You feed battery power to both middle terminals and the load to L1 through L4 as needed.

Feed B+ at 2 and 5. Park and dash lights at 4 and 6. Headlights at 3. You first need to find which is positive power and what the other wires feed by applying power to them one at a time.

[dickandlois]

The picture of the switch Ray posted, fits your description.

The key item to keep in mind is the current rating of the switch and the current needs of the lighting circuits.

Should the total current requirement of the parking / marker lights and the headlights exceed the max current of one section of the switch. By installing the style of switch pictured and supplying power to both center terminals would in effect increase the current rating by 2. IE - 6 amps per contact for the set of contacts would be increased to 12 amps total.

So connecting the two contacts L1 and L3 in parallel would supply power to the headlights and marker lights when they are on. The head lights draw around 5 amps each @ 12 volts for 55 Watt bulbs that equals about 10 amps.

The marker lights(20 of them)depending on the location of the bulbs, 16 side marker lights and 4 corner marker lights would require about 15 amps.

Rich.

Note, Could you post the current and voltage rating of the switch? and any additional information that was supplied with the switch. It would be something like 10 amps at 32 volts or 32 volts @ 10 amps. The voltage rating and current rating might be a lot different then what I posted.

[huffypuff]

Good catch of why the switch is designed that way Rich.

[wolfe10]

Using a relay to power the headlights (usually two, one for low and one for high beams) is relatively inexpensive and a reasonable upgrade.

That way the switch only handles less than an amp-- the power needed to close the relays.

Will give brighter headlights as well due to less voltage drop.

[kaypsmith]

Ditto Brett!

[huffypuff]

Above is how to add the relays. Note the power wiring to coil number 86 of relay comes from dimmer switch.

[dickandlois]

Brett and Ray. I totally agree with using relays ! Interesting that they used a toggle switch for the lights.. More common to see a pull / push switch for the lights.

The setup on this coach is something I have not run into.

Nice drawing attachment Ray !

Rich.

[huffypuff]

You can also buy a prewired harness to make the job easier. I should of done this to my 1993 Southwind as it had a Ford push pull headlight switch and floor dimmer. I always hated how dim those headlights were but lasted until I traded for what I got now.

[RHUGGETT]

Thank you guys for all the information. I'm sure it is going to help me solve this problem. I really think that the problem has developed from the electrical technician who had worked on the original problem with the parking lights. Since I very rarely drive late in the day, I only recently discovered the problem when I eventually did a drive at night. The motorhome is parked in a storage lot for the winter, but when I go to run it I will definitely see if I can check out the wires. I am thinking that I will get a couple or relays and insert them into the circuit as you suggested. I will let you know how thing work out. The wiring for these lights is very basic. with wires just connected on the switch terminals with push on terminals and they look like they have been mixed up.

Thanks again for taking your time to help me out.

R Huggett