Alternator

[Guest timswait]

I've always hated the bulky Sierra alternator, and after it nearly dropping off in Europe I've decided to change it for a more compact one. I've got one from the scrappy from a Toyota Corrolla, either '90 or '96, I couldn't make up my mind on the hierogliths scrawled over. Anyway's I'm fabricating up a bracket and reckon I can get it to fit much nicer than the old one, but I'm trying to work out how to wire it up. There's three spade connections on it and one post. I'm guessing the post is to connect to the battery +ve, probably one of the spades is for the instrument cluster, any ideas on the other two? I can test it with a multimeter once I get it fitted with the engine running, but any ideas what the pins should do?

Here's a photo of it:

[Longboarder]

Voila. The three small terminals are as the pic. Needs an ignition live to get it going, ignition warning lamp output and the third terminal is not used. Big post is battery positive as you thought.

 

Nigel

[Guest timswait]

Fantastic, cheers for that, the speed with which you get answers on this forum never ceases to amaze! Just out of interest, what car was yours off, looks identical to mine?

[Grim]

suzuki swift?

[Longboarder]

Suzuki swift. You looked at it at Barkstone.

 

Nigel

[Guest timswait]

Hmmm, something of a qualified success.......

Fabricated a fairly neat (for me!) bracket, and improvised a tensioning system, it fits nicely into a small space, far from the exhaust manifold (unlike the old one) and with better clearance from the steering shaft. The old belt is too long so I'll have to get another. I've improvised a belt from cable ties (is there nothing they can't do ) and starting the engine has it spinning nicely (although it probably is slipping, I can turn the alternator pully by hand without turning the crank). That's the good bit, the problem is the battery light, which doesn't go out, I wired it as in Nigel's diagram but on starting the battery light on the dash wouldn't go out. I've disconnected the chunky wires from the post and measured the voltage on the post. Initially after starting the engine there is no voltage on the post at idle. However after blipping the throttle and letting it settle back to idle the voltage on the post is 21V. Connecting the multimeter as an ammeter in series between the the alternator and the battery connections I get 1.5A into the battery, so I think it is working, it's just the light which isn't. The light is an LED, it worked on the old alternator, although you did have to blip the throttle to make it go out and start charging. Any ideas on why it's not working now?

P.S. I've just looked at the wiring diagram in Haynes and a fat lot of good it did me. Does anyone understand how this circuit works or is it witchcraft? I traced the wire from the alternator back through the warning lamp to the TAILGATE RELAY What sort of madness is this, or misprint in Haynes maybe?

[Guest hypermick]

Tim,. first impression it sounds like (with 21v there) that alternator might have used an external regulator on the original car,. many Japs did.

1.5a charging rate sounds on the low side.

 

If you had it directly off the scrap car it might pay you to go back and have another look under the bonnet. Alternatively you may have to do some research via a factors or auto electricians (assuming it came out of a pile of units) to make sure youre heading in the right direction with its application.

Basically if it needs a regulator you'll never get it right without it.

 

 

mick

[Guest chris brown]

The light is an LED, it worked on the old alternator,

I'm very surprised it worked at all this light is one that has to be a bulb as it is the current through it that starts the alt working in the first place so not only has it to be a bulb but one of the correct wattage.

[Guest timswait]

I'm very surprised it worked at all this light is one that has to be a bulb as it is the current through it that starts the alt working in the first place so not only has it to be a bulb but one of the correct wattage.

I think that was why I used to have to blip the throttle (to 2000rpm) to get it to cut in. Once it cut in it stayed cut in, so I couldn't be bothered to sort it out properly. I could try a parallel resistor with the LED to draw more current through it.

that alternator might have used an external regulator on the original car

Do you have an external regulator, Nigel? Unfortunately I got mine off a shelf, so I couldn't find out much about it, it was only a tenner though.

1.5a charging rate sounds on the low side.

Could have been the cable ties slipping, I'll buy a proper belt tomorrow, also the multimeter wasn't very well connected, it kept sparking and burning my fingers, so it might have been more than this...

[Longboarder]

Regulators inside the unit. An ignition live feed in to one small terminal supplies the volts to get it charging. The warning lamp doesn't do much apart from tell you it is charging.

Suggest you get a proper belt for it, make sure you have the correct three connections and the right way round!!! and try again tomorrow.

 

Nigel

[Guest timswait]

Just driven to Halfords (note: cable ties don't make an acceptable fan belt, it broke twice on the 3 mile journey there! ) got a fan belt which fitted (after 3 attempts of fitting it in the car park ) and drove home, all the while the warning light on the dash staying resolutely on, not even flickering. However before I left I measured the battery voltage as 12.6 volts, on returning it was 13.04V, so I can only assume the alternator is working, it's just the light which isn't. Nigel: do you have any diagrams for how you wired your lamp up? I'm just about to try putting a bulb on it and seeing if that works.

[Guest timswait]

I've now tried it with a light bult, as opposed to an LED, connected between the ignition live and the warning light connection on Nigel's photo. The light lights and doesn't go out, just like the LED did.

[Guest timswait]

I'm pretty confident th alternator is working. I measured the current into the battery as 14Amps briefly, before pulling the meter off because it's only rated to 10. I've measured the voltage across the battery with the engine running. With the alternator disconnected it was 12.4, dipping to 12 when I turned on all the lights. With the alternator connected it was 14V, dipping to 12.9 with the lights on, but going back up to 13.7 when I revved it. Do these figures sound right, they seem reasonable to me?

[Longboarder]

No need to measure amps. Bad practice to run the engine with the alternator disconnected. It can kill it. Volts seem reasonable. Wiring is as below.

Check you haven't got the two thin wires the wrong way round and that all connections are good including the engine/battery earth connections. Using an LED for the ignition light can be fraught as it is much more sensitive than a tungsten bulb. The picture below is exactly how mine runs without any problems and no reving to put out the light.