Rear tow hitch lights?

vlamgat · 08-02-2021, 12:08 PM

I made the huge mistake of not checking these on delivery or since. Last night tried to hitch up in the dark and found the lights supplied by Dynamax do not work. The Aux switch illuminates; the wiring of the Aux connection to #1 looks solid; the fuse is not blown as presumably the Aux #1 light would not illuminate but to check the JCase fuses as installed really requires you have a spare to hand because removing it will destroy the fuse as there is only one reachable edge to grasp it.

Also checked the E-brake was applied and in P and N; with/without ignition although settings are for Battery use; and checked connections to the lights.

Is there something I am missing? Something at the back of mind says there could be a safety limiting switch somewhere that prevents you from driving with what might be termed back-up lights illuminated?

Desert Boat · 08-02-2021, 12:58 PM

The 28ss chassis wiring diagram shows it goes straight from the aux interface under the hood to the rear cap plug, red/black, (DAB). So it should only be controlled by the settings for the aux switches. These are only momentary/latch and battery/ignition.

While I have not tried it, it appears you can leave them on while driving.

**bclemens** · 08-02-2021, 01:02 PM

I don't know of any safety lock out, so I would not waste any time trying to get them to work in various engine/brake scenarios.

Voltage at the light?

vlamgat · 08-02-2021, 01:18 PM

Quote:

Originally Posted by bclemens

I don't know of any safety lock out, so I would not waste any time trying to get them to work in various engine/brake scenarios.

Voltage at the light?

Yup, just waiting for the rain to pass but that is the next test.

vlamgat · 08-02-2021, 02:33 PM

No power at the lights or at the output from the dark grey Aux/upfitter outlet.

Lost the top of the fuse when I removed it so the internal connections are very visible and completely intact.

So something is withholding power from the upfitter even though the indicator light is illuminating. Possibly the upfitters have a unique grounding and I am measuring their output incorrectly when sourcing the ground from a ground on the chassis? Swapped relays with #4 but still nada.

**bclemens** · 08-02-2021, 04:14 PM

The only other quick thing is to look at the switch programming. Make sure it is set up properly in the cluster.

vlamgat · 08-02-2021, 04:26 PM

That was my first thought. So reviewed the set up for all 6 Aux. #1 is definitely set at Latched and Battery as is #3, 4,5 and 6. I also checked to see if any of those were connected but only #1, and 2 by Dynamax; #3 and #6 by me.

Checked for power at the fuse, there was none so it seems something has gone wrong with the Aux #1 control but this is hard to rationalize when the indicator reliably comes on.

vlamgat · 08-03-2021, 08:55 AM

Now confirmed there is power at the switch at indicator light shows and at the fuse where I had previously sourced a poor ground.

So the problem lies in the Dynamax wiring between Aux 1 terminal and the lights.

Another QC issue. Makes 9 on my coach. Wonder what comes next.

**bclemens** · 08-03-2021, 09:00 AM

Quote:

Originally Posted by vlamgat

Now confirmed there is power at the switch at indicator light shows and at the fuse where I had previously sourced a poor ground.

So the problem lies in the Dynamax wiring between Aux 1 terminal and the lights.

Another QC issue. Makes 9 on my coach. Wonder what comes next.

I do know we were short harnesses for a while. So that line might have had to be hand strung, after it was built.

vlamgat · 08-03-2021, 12:17 PM

Quote:

Originally Posted by bclemens

I do know we were short harnesses for a while. So that line might have had to be hand strung, after it was built.

It does look like that with connectors at the front end and the rear, both looking hastily constructed with the shrink insulation unfinished. I will trace it as far as I can but at the moment I cannot verify there is power at the first one next to the Aux module so i may get lucky!

**bclemens** · 08-03-2021, 04:03 PM

OK, I was mistaken. The harness that we were short was for the M2. The 5 series had the docking lights built into the chassis harness.

Per electrical engineer: "we make the connection for the dock lights under the hood using the dodge interface connectors (see attached). Dock light wires are in the chassis harness. Drop 88 to tail light harness connector drop 1"

vlamgat · 08-03-2021, 05:43 PM

Super helpful. Thanks.

vlamgat · 08-04-2021, 01:12 PM

Quote:

Originally Posted by bclemens

OK, I was mistaken. The harness that we were short was for the M2. The 5 series had the docking lights built into the chassis harness.

Per electrical engineer: "we make the connection for the dock lights under the hood using the dodge interface connectors (see attached). Dock light wires are in the chassis harness. Drop 88 to tail light harness connector drop 1"

Solved: The Delphi GT280 interface connector has parted (again) despite both ends of the loom being well secured to the upper tow bar with tie wraps. It seems there is no positive locking on my connector pair and they are inclined to pull apart. So I secured them together with a tie wrap and tied the looms.

I believe there is a positive lock on the Delphi connector (white tab that must be pressed inwards but mine wont shift. NBD - next night hitch (Winter Is Coming) should be a breeze.

Thank you Brian.

**bclemens** · 08-04-2021, 01:19 PM

all's well that ends well.

vlamgat · 08-04-2021, 01:25 PM

Quote:

Originally Posted by bclemens

all's well that ends well.

I am sure I will find a use for the 40 feet of wire I bought to rewire the lights.

Oh well - projects abound!

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