Reverse B/U lights not coming on, what could be the problem

[wealthwise]

I'm testing the lights before heading on our trip and I'm struggling with two separate issues, that may be related, one is the right turning indicator is on steady when I have the ignition on, checked those bulbs and they are fine, the second is the backup lights don't come on when I put the gear in R, checked those bulbs and they are fine need to test for current, trying to find my multitester lol. yesterday I had it and checked for current at the tow package connector and nothing, also checked the backup fuse and that's good too, could it be a short in the harness? I will be towing a Uhaul Auto transport, the last time we towed through them we they didn't say anything, but here in NM will they let me rent if the the b/u lights don't operate?
Thank for any help or suggestions. Fount the meter going to check current now.

[Captain_Obvious]

As weird as it sounds, if it is a Chevy chassis, it could be your multifunction switch. I was surprised at how many different lighting components run through it. Even the brake and reverse lights tie in.

[wealthwise]

Ok, well being the kind that jumps to conclusions and gets confused, I panicked, upon further checking I was not looking at the rear axle but rather the trani bell housing, the transaxle plug is there just like I had seen it last time, I can breathe a sigh of relief, although I will have the fluid checked at Speedco in Kingman enroute. Meantime I will post those harness pics.
Thanks

[wealthwise]

Started another thread on the missing plug issue, sorry I went off topic

[wealthwise]

enblethen wrote:
Check your fuse panel. Some rigs have separate fuses for the trailer connector.
Turn signal indicator on with lights, indicate a lamp outage.
Verify brake lights? Clearance lights?
Have helper operate lights. Verify that bothe sides of the rig are lighting up the same on each function. Headlights & clearance, turn signals, four way flashers and brake lights

Can't seem to find a fuse that's for trailer connector.
Ok all that checks out for the most part,while I was under the rear looking at the harness I took some pictures of the harness and then I noticed something very disturbing, correct me if I'm wrong, but isn't the the differential where the rear axle fluid goes and there is no plug and no fluid, I could have sworn I looked at that plug a few weeks ago, it requires a wratchet to remove, is it possible it came loose and last time I fired up it came out, I can't find it anywhere, is this hard to replace? How do you add fluid? If that's the case I need correct this ASAP, I know this should probably be separate post but this priority over everything else at the moment , wouldn't you agree?

[enblethen]

Check your fuse panel. Some rigs have separate fuses for the trailer connector.
Turn signal indicator on with lights, indicate a lamp outage.
Verify brake lights? Clearance lights?
Have helper operate lights. Verify that bothe sides of the rig are lighting up the same on each function. Headlights & clearance, turn signals, four way flashers and brake lights

[wealthwise]

enblethen wrote:
Back up lights use a common source. Follow wiring between the two. Check connections where the trailer connection ties into the system.
Different rig then in signature? make, model, chassis would help. Sounds like Chev chassis.

Ok will try that, yes it's a 94 allegro bay DP, I tried to change it in the sig but it won't take, can't figure out why. So here are my latest findings, I checked the Uhaul connector and I have current for turn signals but no current for running lights or break lights, is that normal? As for the left turn arrow indicator going on it was when I turn on running lights, and that was an indicator that the left bulb was not on, seems to be an issue on the connector itself, luckily it does not affect the turn signal itself. As for the b/u lights, I suddenly realize how often do you back up with an auto transport anyhow? I checked on Uhauls sight and it says "all lights" must work on the tow vehicle, so it's up to them I guess.
Thanks

[enblethen]

Back up lights use a common source. Follow wiring between the two. Check connections where the trailer connection ties into the system.
Different rig then in signature? make, model, chassis would help. Sounds like Chev chassis.

[bsinmich]

On a 30 year old coach I would seriously suspect ground connections every time there is an electrical problem. Fiberglass does not conduct so there always has to be a ground on everything.

[wealthwise]

enblethen wrote:
Steady turn indicato would show you have a lamp outage on the right side. Yes, problem could be related.
Go under rear of rig and check to see how the lamp grounds are achieved.
Do you have turn indicators on mirros? What about mid side?
Back up lights is not a required lighting.

Ok will do that, on indicators on mirrors rig is a 94, mid side is just runner lights, as for Uhaul I think the transport has it's own lighting system. I just went to check for current at the bulb connector, there is none I followed the harness and checked for current with ignition on and in R, one shows about 11, the other has only .2 looks to me like that's the culprit but that's at the end so who knows where if in the harness the problem is I'm going to try to trace it. Meanwhile I will check the lamp grounds, since I was having an issue with the right parking light not coming on, only came on when I took out the connector and put it back, maybe there is an issue there?
Thanks

[enblethen]

Steady turn indicato would show you have a lamp outage on the right side. Yes, problem could be related.
Go under rear of rig and check to see how the lamp grounds are achieved.
Do you have turn indicators on mirros? What about mid side?
Back up lights is not a required lighting.