Replacement headlight switch

[oldie]

As mentioned in an earlier post lovely new acquisition has a severe electrical drain, emptying a new 80Ah battery within four days. Investigation required. My initial culprit is the headlight switch which remains continually illuminated. I understand that it has back-up information within and needs to match that of the IPK. If I fit a replacement can a t4 session make it compatible with the correct information?

Also I understand it may be worthwhile replacing the alternator. It looks easily accessible. Is it a straightforward task? Any specific tools or concerns in the task?

[David]

...Also I understand it may be worthwhile replacing the alternator. It looks easily accessible. Is it a straightforward task? Any specific tools or concerns in the task?
10 minute job; no special tools needed.

David

[David]

10 minute job; no special tools needed.

David
Tip: Give it a try holding back the tensioner (square 3/8" drive-end, I use a ratchet) and then you can check the pulleys for noise, roughnes or excessive play before you order your alternator simply because, if it appears that you need new idler-pulley(s)/tensioner, it may be more cost effective to order them at the same time.

RockAuto do a kit with pulleys, tensioner and belt at a very reasonable price I note: http://www.rockauto.com/en/catalog/ford,2003,mustang,4.6l+v8+sohc,1415089,belt+drive, belt+drive+component+kit,10660?a=Referer+www9.mg-cars.org.uk+URL+%2Fen%2Fcatalog%2Fford%2C2003%2Cmu stang%2C4.6l%2Bv8%2Bsohc%2C1415089%2Cbelt%2Bdrive.
(Alternatively new bearings can be fitted into idler-pulleys and tensioner, I understand, but I've not done that myself).

David

[Nich]

If I were you David I would isolate the battery drain first. As you say it may well be the light switch module but could well be lots of other things as well. If you fixate on the LSM and get it recoded you may still have the problem to solve.

Nich.

[oldie]

Undoubtedly the battery drain is my priority. I'll put a multimeter into play tomorrow and read the difference, if any, when the LSM is completely disconnected. If that is the source I'll obtain a replacement. It will be a relief if that proves to be culprit.

[WNJ516]

Hi Oldie, let us know what the drain is before and after isolating the LSM, i can tell you my drain is approx 95ma after everything shuts down, and i can leave my car 5 weeks and it starts ok.

[oldie]

I used a multimeter today. My understanding of them is hazy but I think I had a reading of 200+mA (0.2). When I unplugged the LSM it seemed to give a lower reading. However my caveat is it is possible the scale was not correctly set. I've reconnected the battery (reading 12.5v) disconnected the LSM and I'll check the drop, if any(!) tomorrow. The drain must be a longstanding problem with this car for as I look around virtually every ancillary item is unplugged.

[scooter]

Try unpluging all the wires from the alternator it could have a faulty diode.

[David]

Try unpluging all the wires from the alternator it could have a faulty diode.

Déjà vu for me on an 827 years ago; was just that. Good tip!
Don't leave that disconnected fat live cable hanging around unprotected, 'oldie', else you may (literally) flatten your battery in a lot less than 4 days !!!!

David

[oldie]

Since homing in on the LSM as a likely cause of the major drain I've taken to having the battery connected but disconnecting the LSM overnight. Yesterday I checked the voltage at midday, dropped about 0.1v-ish, quite cold for Sussex so a promising figure. Started first turn. Battery charge <14.5 when running. Then did a hardware swap. Switched the LSM from my v6 into the v8, no illumination. Then put the v8 module into the v6 and "let there be light". It would appear a replacement is required. Marinabrian has a recoded unit available for me. It'll be a pleasant surprise if that proves to be the solution. One or two water leaks to trace next.

[David]

Fingers crossed for you, David .

David

[oldie]

Replacement, coded LSM seems to be doing the business. Car started first turn yesterday morning after standing idle for a week. I feel tempted to go for another trip today.

[David]

Replacement, coded LSM seems to be doing the business. Car started first turn yesterday morning after standing idle for a week. I feel tempted to go for another trip today.
Congrats; fingers crossed! Make sure you've got enough on you for a bus ticket :)

David