Hi

I have developed a problem with my TL AWD Magna 92004, 115K km). My battery light starts to flash when i turn the car off for a short time when warm and then restart (e.g. gone to shops). After a short period (perhaps 15-60 seconds) the light will go out. I have now noticed it flickering on and off occasionally when travelling irrespective of stoopping, but a quick rev and it tends to disappear. I have now noticed the ABS warning light has flashed a couple of times and then goes off.

Any ideas? From reading other posts on here i was thinking it could be the voltage regulator or brushes in the alternator? My battery is around 18 month old so i dont thats the problem as its topped up ok. Given I dont have a multimeter and dont have the greatest mechanical skill is the first thing to do replace the voltage regulator unit and then go from their, or just the whole alternator as a best precaution? Whats a reasonable price for an alternator?

Put a volt meter across the battery when its idling, maybe rev it up and down slightly, and look for voltage fluctuations. A fully charged battery and good alternator will give you about 14 volts, steady. Do this with high beam on/off to see how you go. Voltage fluctuations mean the alternator is having problems, may be the brushes or regulator, or armature, or diodes, or . . . .etc. lol

At your Kms it would be unusual for the brushes to be worn but it does seem like brushes worn and/or sticking in the holders - I'd replace the regulator/brush assembly if the brushes did prove to be worn when removed for inspection (2 screws)....I'm not sure why the ABS light would be coming on as well but I guess it's voltage sensitive too. A new reg/brush assy is about $60 presuming you have the Bosch alt......but if you'd prefer not to DIY then that is not an option. It also could be caused by loose/corroded battery connections. I've got a brother who had similar problems with the light coming on intermittently and his was traced to a bad diode which reached the stage after 3 weeks when more diodes went bad and the battery discharged totally overnight - this was in a TD42 Patrol. A loose drive belt may also cause this problem although I'd guess it would squeal as well.

I've got a brother who had similar problems with the light coming on intermittently and his was traced to a bad diode which reached the stage after 3 weeks when more diodes went bad and the battery discharged totally overnight.


A blown diode is easy to diagnose, just feel the alternator when the engine is cold, say first thing in the morning before you drive it. If the alternator is hot you know what the problem is! lol

A blown diode is easy to diagnose, just feel the alternator when the engine is cold, say first thing in the morning before you drive it. If the alternator is hot you know what the problem is! lol

In my brothers case initially it was an intermittent diode failure, and this caused to charge light to flash intermittently....so it did not flatten the battery till 3 weeks later when it failed completely and probably then made the alternator very hot, but it certainly did not heat the alt initially. I always thought diodes either worked or they didn't - cut and dried - but it appears they can develop intermittent faults. Not much help to the OP!! I'd go see MadMagna for a 2nd hand unit or advice.

Would not bother with just a brush replacement, you should either get what you have rebuilt, get new alternator or even a secondhand one. Some do seem to go quite early, why we dont know, but then others seem to go for 300+k's

Would not bother with just a brush replacement, you should either get what you have rebuilt, get new alternator or even a secondhand one. Some do seem to go quite early, why we dont know, but then others seem to go for 300+k's

I agree with Mal. Charging systems are finicky little things - and if part of it goes weird it's best to have your alternator rebuilt or get another, as the costs are realtively low.

Compared to motorcycle charging systems, cars are a piece of cake - the regulator and generator are one unit! Take it out, drop a new one in, job done.

yeah had the same problem with the TJ about a year ago, just changed the regulator and its going fine, should of had it rebuilt but had NO money at that point. The regulator and brush holder are one unit, so you never change just the brushes, you change the whole regulator instead. Will cost about $55 for a regulator. Not recommened to replace just the regulator though.

At night when the battery and ABS lights flicker you will probably notice all your dash lights go brighter, this is because its overcharging and the ABS computer is indicating a fault (too high input voltage). This indicates a faulty regulator.

I recommend a reconditioned exchange unit which will probably run about $180-200.

If you just want to go the regulator route you need an RE72 bosch regulator.