TD42 Alternator.

[Toyeatre]

It would seem my alternator has just recently decided to act a bit strange.. When I first start it, it has always fluctuated with charging, for the first minute or so, the needle on the gauge would flick up and down.. Have replaced the alternator 3 times over the years.. and they have all done it.. So I havent really been bothered about it.. But... Now.. it has changed a bit.. (Seems to have started it since the weather has gotten colder)

It seems that now.. when I first start it.. It doesnt want to charge at all.. About 5 minutes of running/driving... it will come up to be charging at around the 14.4 volt mark..

Is something on the way out.. Am I going to have to rob another bank to get a new Alternator in the very near future?

[ITS A FORD NOT A NISSAN]

could just be stuck brushes
or a diod or something has blown and the alt is only on half power

[Morrygq]

mine did the same thing recently, light coming on then would work again etc
i bought some bushes for $8 and put them in and it's as good as new[but muddier].
it's easy to do and a cheap and quick check to take off and inspect.
if need any help let me know.
mine is a bosch alternator.if it helps.

[Tracteur Tom]

Toyeatre, check the charge light circuit. The alt requires a small current - supplied by the charge light - to start. Without it, the alt will only start at high revs. Sounds about like your problem ?

[90MAV]

Hope you're not using the dash gauge as a charge indicator, they are notoriously unreliable. Mine shows 16V+ when battery voltage is spot on at 14.4V.
Get someone to check what's happening at the battery before you spend big bucks for no reason.

[whistler]

Checking the charge light circuit is correct and often it is the 15amp engine fuse that causes the problem, pull it out and if there is oxide on the contacts you have dry joint. Just clean all the contacts you may find the alternator charge kicking in quicker.
Cheers from
Ralph

[Selfy]

an auto sparky told me that if your fuel filter light is not working the alt COULD have a problem (check the globe first) as the filter light is in the same circuit as the alt feed wire that Phil pointed out

cheers Selfy

[Tracteur Tom]

There are a few dash lights that are "tested" by the WL ground return circuit though the alternator when the ign is turned on and before start up. Brake warning / Fuel level spring to mind (there are others auto trans etc) and they connect via diodes to the alt warning light/alternator.

[dicko1980]

Hi

i just replaced the alternater on my TD42 and am suspect that the alternater is only charging at higher revs, so my question is how do you check that the charger circuit is working and which fuse do you need to check to see thats its not blown?

cheers
dicko


Checking the charge light circuit is correct and often it is the 15amp engine fuse that causes the problem, pull it out and if there is oxide on the contacts you have dry joint. Just clean all the contacts you may find the alternator charge kicking in quicker.
Cheers from
Ralph

[MQ SWB#14]

get hold of a multi meter and then take your battery leads off check the chage in the battery and then put theem back start th engine and then check it again 14.4volt is way too high and can hurt batteries they should have 13.5 - 13.7

[Tracteur Tom]

Easiest way to check the charge light cct is by looking at the lamp ! On when engine is not running, off when its running ! If the bulb is no good or it doesn't light or go out then the problem is somewhere in the cct. Look at the wiring diagram, all will be revealed.

14.4 V is - correct me if I'm wrong - the alternator regulated voltage, it is on Bosch alts anyhow ?

[GuJohnno]

I had an issue with my alternator not putting enough charge out the back of it. By the time it reached the 2nd battery in the back I was only getting about 12.8V
My mechanic got a new one in and bench tested it and it was putting out 14.5V
He then pulled mine out and bech tested it and it too was putting 14.5V out.

He then started looking at the wiring and replaced the -'ve lead comming of the battery to the body.
Replaced the -'ve battery terminal.
Ran a lead directly from the back of the alternator to the +'ve of the battery.
Replaced the corroded end of the dualbattery sytem where it connected to the +'ve of the main battery.

I now get about 14.2-14.3V the the battery in the back of the car.

May not be applicable to the original post but good food for thought.

Johnno.

[Tracteur Tom]

I see this time and time again. Good battery, alternator and starter motor wiring is key for these things to work as they should. It pays to spend as long as it takes removing each connector, clean each mating face with wire wool and replace using silicon grease to keep out the air. and you dont need pay an auto lecky to do it !

[Toyeatre]

Thanks for all the info guys.. Just an update on my part... Seeing as I havent posted any follow up in a thread I started... :)

With regard to my intermittent charging initially.. I found the problem.. totally by accident... litterly.. It would appear my belts werent too flash.. condition wise.. The alternator one snapped... Causing the power steering one to almost jump off its path too... Was close.. The clutch gets mighty hard with no vaccuum... And the brakes... wellll.... what brakes!!.. Barely missed a nice new BMW.. Wasnt pretty...

Anyway.. replaced ALL the belts... and the water pump (different issue).. Now its back to normal... so to speak..

It still appears to cycle about 3 times before remaining charging... It has done this since I bought it waaayy back in 1998.. And has continued to do it through the two alternators I have replaced in the past. So.. not worried about that bit now..

What it is doing now tho.. Is
1. Dropping the charge right back to well under 13v at idle.. ie.. increases charge with revs..

2. And I appear to now be getting some feedback through the radio.. like in the old days with my old petrol cars.. the alternator whine/feedback...

I am no where near an Auto lec.. so.. any more pointing would be appreciated... :)

Thanks.

[Tracteur Tom]

I suspect the idle speed is too low for the alternator to kick in at full volts, mine does this to, just above idle and all is well. I don't lose sleep over it.

There should be a suppression capacitor on the back of the alternator to stop any whine on the radio. Check its still there and connected properly.