Gas door and trunk not opening.

[Maddawg]

So I bought another Jetta TDI. A 01 in decent shape and 290000 kms. Now the fun begins. Gas door and trunk not opening.I pulled the actuator out of gas door and tested . Works fine. Don't hear any attempt of opening either trunk or gas door when using switches or key fob. Fob could have dead batteries. I took door apart and pulled switches. I used my meter on continuity . Single pole on switch to ground and touched other poles while working switch and got the beep. Think I did it right anyway. I tested the plugs for the switches and only got .5 volts while meter was set to 20 which is lowest setting. Tested battery to make sure of setting. I'm assuming there should be 12 volts going to these switches. I went to junk yard and got more switches and plugs for them. Cut 1 ft of wire with them. Don't have a chance to test as I'm away working for the next 4 days. Shouldn't there be 12 volts to plugs even with key off and am I testing correctly as I'm only guessing without a diagram which I would have a hard time reading anyway? Hopefully I'm on the right post also. Thanks and I'm sure I'm not the only one who has had this issue. Looking forward to being on the road again with this Das Auto. Lol

 

[Vince Waldon]

On the 2001 both the gas door switch and the trunk switch are simple coil actuators directly driven by (flimsy) contact-type switches in the driver's door...no relays to carry the actual current, unfortunately, and the gas lid is independent of central locking. Over time back-EMF from the actuator coils arcs the contacts and they develop enough resistance to prevent full current flow to the actuator(s); if you measure voltage at the switch you will see a lot less than 12V on the far side when this happens.

So, the usual fix is to remove the switches, spray with a good contact rejuvenator like DeOxit, and motor on for another 100K. Switches from the junkyard may or may not be in the same state.... kinda like arm rests and glove box doors.

If the trunk won't open with the fob either there may be something else happening there. The common failure mode specific to trunk electrical stuff is broken wires in the wire harness that flexes as the trunk hinge opens and closes. Last car I did had 4 wires broken; I was actually troubleshooting a licence plate light that would not work, even with a replacement bulb. How's your licence plate lamp?!

 

[n1das]

None of my TDIs ever had a GAS door.

 

[Maddawg]

Thanks. I tested plugs from the car to the switches and got .5 Volts. I did not check the licence plate light though. I'm hoping I don't have a short to the switches. I won't be able to t/s till Monday night till I get back home from work but I will definitely look at plate. Also didn't check fuses. Duh. Just bought her and was in rush to pick up window switches from junkyard before they closed.. if there was a picture of switch plugs and what to test for voltage on site that would help for sure. Been at work since Thursday and not able to t/s till Monday so not much else I can tell you right now other actuator did work out of vehicle when I powered it up with 12 volts. Thank you and will get back with results on fuses and licence plate light.

 

[Vince Waldon]

To be clear, the licence plate light is just a clue that something might be amiss with the entire harness... or not.

And yup... fuses are probably the first thing to check.

 

[Gilty_one]

Check the condition of the wire harness where it enters into the trunk... the wires tends to get stretched where the cable loom moves with the trunk opening and closing.

 

[Maddawg]

Ok. So there's only .05 volts when testing plugs for the switches. I got my brother to try the actual switch and tested voltage to actuator plug on gas door. Got .11 when he used the switch. Fuse was fine as its for the windows and door locks also .With the switches pulled I tested the plugs and got only .05 volts. There should be 12volts I would think. Hate wiring issues. Got actuator unhooked on gas door and using key for trunk for now. Gas door is spring loaded so not flapping around but sucks nevertheless.