Reverse lights doesn't work and I don't know were the wires are connected

I tried the DIY service and repair manuals from a website and it actually helped me repair transmission problem in my jcb 3cx site-master. it wont move forward or reverse, engine is good both solenoids for forward and reverse work.
I don't have much technical knowledge but I just followed it step-wise, and works perfect!
got it from www.reliable-store.com

Check any ground wire you can find. They may have gotten corroded and no longer grounding properly.

also I would check both fuse boxes and make sure there aren't any blown fuses.

Old new beetle VW harness has contact resistance problems(vibration of wires) and needs to be recrimped the long wires(vibration can be stopped by silicone rubber anchoring). Cold weather make battery voltages low and needs recharged with handbrake on(headlamps off) 10 minutes warming engine up the whole winter.

This is a failure of the "remote function actuation module". It is located under the rear deck next to the right rear speaker. The rear seat must be removed to access it along with removing the rear deck. It controls the trunk release, door locks, dome light, and reverse light. My remote trunk release stopped working along with the relase button on the dash along with the reverse lights failing at the same time. The module is over $150 so I would try to find a way to rewire the lights to work without the module.

Without knowing what it is doing exactly I would say if it does nothing when you turn the key then you are probably looking at an ignition switch problem. If it cranks but doesn't start it will probably be a battery problem. Since you changed the battery thinking that might fix it I'm leaning towards the ignition. The thing you are looking for is attached to the bottom of your steering column and has a bunch of wires running to it. Simple to replace just detach the wire harness and unscrew reverse for install. The cost of box may be what gets you. I don't know what 1 for your vehicle would run so it may be reasonable enough. Hope I could help.

Hi Harlan.

I see that you mentioned a 1999 Dodge Grand Caravan in your other question. I assume this question is about the same vehicle.

The checkup will start from the fuse and relay in the power distribution center. A way to test the relays is swapping two relays of the same kind to check if that makes any difference.
If relay and fuse are OK check the wiring to power distribution center, check the dimmer switch and the connection to BCM (the module under the dash).

I have uploaded relay map and wiring diagram at this link. Please click on the link. If necessary click on the picture again to enlarge.

Regards.

This can happen when the wires to the lights come loose. If you know someone who can get in the back and check the wiring, and can hook them back up, that's probably all it is. Sometimes items in the trunk, or the back of an SUV, or just hard road bumps can shake the connections loose.

Connect a Test Light between the ground wire on the light socket (bulb holder) and somewhere on the body (a clean/bare metal surface) and then put the transmission in reverse.
If the Test Light lights up, you have a bad ground (broken wire, bad/corroded connection). If it doesn't then use a Multimeter to check for power on the Positive side of the Socket, No or Low voltage means a bad wire. Battery voltage is generally 12.45 (without the engine running) and 14.5 (with the engine running) So if you're getting less than that (by more than .3) you have a poor connection or damaged wire

take a 12 volt test light and check the wires at the shifter connection on the transmission,follow the one that goes hot when shifted into reverse. it should lead to a harness connection on the lower end of the steering column. but don't hold your breath. could also be inside console on floor shift models. any splicing must be done with same gauge wire.

You have a short circuit to ground in one of your lighting circuits. If there is any physical damage to the vehicle (collision) near any of the exterrior lights, I would look at the wiring harnesses there first. I have seen many "butcher jobs" resulting in severe damage done by people poking around in the wiring harnesses without knowing what they are doing. This is a good way to give your vehicle an early retirement. I would recommend having the problem diagnosed by a certified technician that does automotive electrical service.

You may also find these articles helpful:

Where's The Fuse?

What Else Could Be Wrong?