gazfish

Took my car for its first inspection here (NCT), the car had an MOT from the UK when I bought it but the testing here is much tougher and they will fail rather than advise on most things. I had fixed everything I could find beforehand, including getting all the external lights working reliably and pointing in the right direction, replaced the track rod ends and checked the bearings. Anyway had the following fails:
1) Rear tires were too old and didn't have an "E" marking
2) Rear outer CV boot ripped, don't know how I missed it
3) Sway bar bushings and drop links worn
4) Tracking too far out of alignment
All things fixable by me or the local tire shop so all good.

Anyway, he couldn't re-start the car at the end of the test on their lift. The battery was dead and they had to push it outside with a crowd watching through the viewing windows.
The voltmeter was not working when I got the car and was low down on my to-do list, but following the above it suddenly became top priority to know if the battery was being charged. Took the pod out and it turned out to be a corroded connector so all good.
Voltage looks good so thankfully it looks like a bad battery rather than alternator/voltage regulator. The battery was only 2 years old but maybe it had a hard life with the PO.

ltoolio

Maybe a drain somewhere from inside the car? Lots of threads on that topic.

gazfish

Hi,

The PO installed a battery isolator switch which I use every time i park the car as the red light on the door is constantly on, another thing on my list, so I can eliminate a constant drain causing the battery issue.
Thanks,
Gary

jeff spahn

We need these inspections in the US to get all the piles of crap off the road.

GuardsTurbo

Bite your tongue.

ezdriver

Should we draw the line at air-cooled, 996s with IMS issues, ugly colors?

FredR

Gary,

Fitting an isolator switch is no solution - it simply alleviates the symptom of an underlying problem that is not going to get better with time. Chasing down such problems can be a real PITA. A good starting point to trouble shooting is to check the temperature of the relays after the car has sat overnight- a warmer one being a clue as to the troubled circuit. A good few years ago I had a problem on my late 90 S4. It was eventually traced to a chaffed wire in the tail gate area that was leaking juice- why it happened was a complete mystery. From time to time these cars need access to someone who is very good with electrical diagnosis so either you learn to DIY or make sure you know someone who knows what they are doing.

These cars have a continuous drain at the best of times [about 30mA is normal on later models as I recall] so a good battery should be able to stand well over 2 months before being totally drained.

In your [cool] neck of the woods a battery should last many years- where I am we do well if they last two years as the heat kills them pretty much irrespective of make.

Rgds

Fred

gazfish

Hi Fred,

I intend to trace any battery drains and solve them once I have the more major issues resolved. I come from an electronic Engineering background so I'm more comfortable with the electrics than the oily bits, but enjoy working on good engineering in any form.

Cheers,
Gary

FredR

Gary,

Your background should help you immensely. Strongly recommend you do a simple measure of the current flowing through the ground strap- to do this you may need to get someone to lock you in the car with the rear seats folded down - takes a few seconds for the alarm system to arm and then you can measure the ampage. Gives you an idea of the magnitude of the problem you are dealing with. to flatten a good battery in two days takes about 0.7 amps!

A common problem at this age with original alternators is a failed diode.

Also a good idea to include a few details with your signature line to confirm year/model- easy to do in your profile.

Rgds

Fred

9two8

Check out the rear hatch latch receiver switch, the electrical contacts at the bottom develop corrosion causing the problem you have with the red door light staying on , I removed mine , cleaned the contact re-installed and red door light extinguished. Never know that might be the problem.

gazfish

Thanks Ken, I'll give it a lash. Looked briefly at the wiring diagram and the red light just seem to feed off the footwell light so would have thought all the interior and door lights would operate together....assuming they haven't been re-wired wrongly by someone given that the wires are mostly brown & brown/white.

James Bailey

Brown is ground, brown white is switched ground......the interior lights have a constant power but do have different positions to allow you to turn them off with the doors/hatch open....also the glove box light can be illuminated all the time if poorly adjusted. Fun stuff The door hatch pin switches complete the ground circuit for the interior lights if the single wire gets loose and touches metal it completes the circuit...

gazfish

Thanks James, the wiring diagram confirms what you said. The two door switches ground the interior lights via the delay relay XXI while the trunk switch grounds the lights directly and in parallel with the relay.