No marker light on Ch613

[dslpwr09]

Has anyone had the problem of no marker lights on the tractor and trailer? The switch is good but its not getting any power to feed it. I can jump the relay (relay is good) on the drivers side inner fender well and the lights work. I try to and power to the connector on switch on the dash and it does not. I've been waiting on Mack to call me back on a copy of the lighting system diagram but they haven't called me back. (this is another topic for this forum)

[hatcity]

If it is the same as a 2001 CX, remove the fuse panel on the passenger side. reach in behind the dash and just wiggle the wires around.

That's what I had to do. Did pull the dash panel off and could not see anything, but by moving them around..no problem

There was a recall for the light switch harness a few years back. Call MACK and see if your truck was part of it.

[dslpwr09]

Hat, thanks, did the wire wiggle thing. Will call Mack in am and see about that recall. Didn't know a thing about that.

[RowdyRebel]

I'm working on the same problem myself. Marker lights quit working after a hail storm came through...in the morning, I moved the wire on the block under the hood (to trailer plug) for the marker lights over to the tail light pin...so now trailer lights are an all/nothing deal. Only lights NOT working at this point are the 2 outside cab marker lights. New dash switch. New circuit breakers, both in the dash and under the hood. New relay under the hood. New light bulbs. I have a partial wiring diagram from the local dealer...on the switch, pin 9 is to ground and pin 10 brings in power to light it up with the dash panel. Pin 1 (35-D-0.8) goes to the turn signal "clearance flash" switch, and pin 4 (35-E-0.8) comes back. Pin 2 (35-C-0.8) comes from the cab & trailer clearance lamp relay (fuse box under hood), but it looks like it might make a few stops along the way. Pin 12 (35-B-0.8) makes it's way to the right & left clearance lamps on the roof, but it looks like they might also make a stop or two along the way. If I put power to pin 12, the indicator light on the switch lights up...but not the lights on the roof. Tested the switch on the turn signal, and it seems to be working as expected. I'm friggin' stumped.

[RowdyRebel]

Ok...so I just tried putting a jumper in between pin 30 and pin 87 on the relay, and the marker lights and the indicator light on the switch all come on (whether the switch is on or not). The "clearance flash" button on the turn signal does nothing to change that. Pin 12 on the clearance light switch (35-B-0.8) now has power...but stuff still ain't working right. Moving the jumper wire to relay pins 85 & 86 doesn't seem to do anything. Relay IS getting power to pins 85 & 30.

[RowdyRebel]

...and now, even with the jumper removed...whether the relay is installed or not...I'm getting a reading of 7.35 volts at pin 12 (35-B-0.8). All I did was spray some electronics cleaner spray into the under-hood fuse box to clean up the connections a bit. I'm officially stumped. Gotta put the dash back together now & run to town...load's gotta get delivered and I have another to pick up, and the both the receiver and the shipper closes in 3 hrs.

[Freightrain]

Ok...so I just tried putting a jumper in between pin 30 and pin 87 on the relay, and the marker lights and the indicator light on the switch all come on (whether the switch is on or not). The "clearance flash" button on the turn signal does nothing to change that. Pin 12 on the clearance light switch (35-B-0.8) now has power...but stuff still ain't working right. Moving the jumper wire to relay pins 85 & 86 doesn't seem to do anything. Relay IS getting power to pins 85 & 30.

Jumping 30 and 87 just bypasses the relay function. Thus the "flash to pass" will not work as I'm sure that just cuts power to the relay coil to turn the light off.

If the relay is getting power to 30 and 85, then I would guess the GROUND side is what is not connected. I can't see the pictures well enough to decifer, but does the 'flash" button interrupt the ground?(I guess 86 pin goes to the flash switch?) Or, is pin 12 actually reading the other side of the relay coil(basically the ground side). I would guess the headlight(or marker light) switch turns the lights on, then the "flash" button just interrupts it.

If you pull the relay, "85" has power? Then "86" should be ground. Flipping the "flash" button should interrupt that ground.

[keg1]

I had that problem with my CH was always in the relay on the firewall

[RowdyRebel]

I was GUESSING (based upon the partial schematics I have) that power was supposed to come through the relay, to the switch, loop through the directional "clearance flash" returning to the switch, then out to the lights. (35-A-2.0) looks like the hot to pin 85, and branches off to (35-A-3.0) providing the hot to pin 30. Pin 86 comes out (35-C-0.8), before passing through 3 symbols or references I'm either not familiar with or simply don't have before going into the switch pin 2 with the same (35-C-0.8) wire number. It goes through the switch to pins 1 (normally closed, wire 35-D-0.8) and pin 4 (normally open, wire number 35-E-0.8). Wire 35-E-0.8 goes into the normally closed circuit in the directional switch (pin 5) before going out to ground (pin 11, wire BK-E-0.8). Wire 35-D-0.8 comes from pin 4 (normally open) on the lamp switch down to pin 8 (normally closed) on the directional switch before exiting to ground through the same pin 11 (BK-E-0.8). Both the right and left cab clearance lights have wire 35-B-0.8 going in, and BK-E-0.8 coming out to ground, so I'd assume that's the same wire that comes out of pin 12 on the light switch, but again just working with a partial, can't tell what all the wire passes through along the way.

[41chevy]

Might help trace the power paths.

.This type of relay is defined as “Single Pole Double Throw” or “SPDT. This term means that the single armature terminal (or pole, pin30) can be connected (or thrown) to two other terminals, pins 87a and 87.

The SPDT relay is one of the most useful configurations due to its flexibility-it can be used as a switching device, to isolate circuits, to interrupt circuits and to interrupt and switch at the same time.

Seem to think your relay is not routing the power from low voltage or low amperes. I'd check the voltage at 85 86 and 30. Seems per the schematic that there seem to be a common connection in the harness for pins 30 (35a 3.0) and 85 (35a 2.0) power supply. That could be your problem. I'd check volt and ohms for the loop between the pair of wires in that circuit or look at the junction point for a problem.