To be frank with you, I never dealt with Audi back up lamp housing, but typically on most cars, the negative terminal of the light housing is connected directly to the chassis. So in theory, one of the two wires should be connected to the chassis near the back. Based on your picture, you have orange and skyblue wires. I am going to take a wild guess and track the skyblue wire to see where it is heading and check to see if it is connected to the chassis. If you have a wiring diagram, then even better.

 

If there is power across the two prongs on the socket the prongs are not making contact with the bulb or the bulbis bad. I'd clean the prongs where they touch the bulb and attempt to bend them so they make contact with more force.

 

Agreed... and kinda what I was getting at with the 'bulb and pins not aligning' thing.


Now, Chefro, is there power to the sockets at all times or only when in reverse?

I'll go through the wiring diagram again...

 

Yes..

 

Ok... Cant find it in the wiring, but the switch is suppose to be under the hood, under the cover by the firewall, left hand side stright back in-line from the pass. valve cover.

Lemme know if you need the diagram.

 

Let's see.

1) The power isn't always there, only when engaging the reverse.
2) I did bend the tabs so would make better contact. The tabs are in great shape, no oxidation whatsoever on them.
3) I may need to break the plastic cover on the power plugs and just connect the wire prongs directly after pressing them a bit, and see if that makes a difference (I'll keep tabs on what wire goes on what side)
4) To chase the blue wire(s) I'll have to tear the whole harness apart. If it comes down to that, it may be a last resort.

5) Lastly, I have the diagram, Jim. (Thanks, by the way for offering it).
I can see that the ground wires are "brown - "br", and the power wires are blue/red - "bl/ro". I can also see the ground's location (98) -- "in rear lid wire harness".
As far as the switch itself, F4 in the diagram, it doesn't have any location specified.
With this being said, my electrical skills are already exhausted regarding this diagram.
--


Hopefully I can get to the bottom of this problem.
By the way, Bentley doesn't cover the switch' location -neither under the "Transmission'" section, nor under the "Electrical".

Thanks guys.

 

Ok.. you have power at the tabs. Why the bulbs dont light I have no clue without looking at them in person.... What you can do is get some of those 'Quick Snap Splices' (see pic) and tap into the harness right before the sockets. Run the wires to the bulbs and see if they work. If they do, you have bad sockets. If not, then you do not have enough power. You might have 12v when checking with a meter, but the actual load of a bulb pulls the voltage down. If this is the case, you most likely have corrosion in the wiring, either power side or ground.

'F4' is where I was trying to show you. My diagram shows it in the engine bay, which seems weird to me. It might actually be trying to show it on the pass. side of the tranny.

The grounds are brown, all of them in the car. My diagram shows the grounds for the bulbs going to 'S218' (Splice 218) in the harness where the rear fog and plate lights meet with them, then to 'S86' where the tail and break lights tie in, then to 'G404' (Ground 404) near the left tail light.

Thats a pretty crappy wiring diagram.

Sorry I dont have a diagram of the Backup Lights... I dont have the tails for some reason either. I have one of the headlights and fogs just to show what a diagram should look like




Quick Snap Splice:

 

Just looked at the location list and the Back-up Switch is indeed located at 'Right rear of engine compartment' as shown.

 

Ok.. found a diagram for you... pm me your e-mail again, its too big for here.

The Back-up switch is for manuals only. The 'park/neutral relay', controlled by the tranny range switch, is what lights the lights in auto cars...This is in the 'central electric panel' with blk/blu and gray/red controlling the relay, and blu/red the power to the lights.

 

Thanks bro. I really appreciate all the trouble.
PM sent.