Car has been elsewhere and has had a new alternator and had the ecu checked, (proven to be ok?) The problem is the car is still not charging. The alternator is putting out 11.45v-12.05v.
I checked the diode ripple which to me looks bad (Drops out to -200mv twice consistently) but i am reluctant to replace a brand new alternator?
The one wire going to the alternator swithces between 0.03v-2.54v approx. every 2-3 seconds? I dont know what is supposed to be happening on this wire and all i can gain from wirring diagrams is that it comes from the Multifunction Control Module1/Relay fusebox/Fascia.
The wire comes from the fusebox in the engine bay to the alternator. I have found the wire going into this fusebox coming from the Multi Func Mod. and it has the same values on it?
Any help much appreciated. Cheers Luke Browne
Also if someone can tell me how they upload their waveforms i can post the diode ripple?

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Peter

Luke i dont suppose you have checked the condition of the battery to gearbox/body earths

Also where has the new alternator come from? if its a motor factors unit then there is a good chance its the wrong type for the car

Steve

Hi Luke, I had a C2 a few weeks ago which had just been fitted with a Recon alternator from A.P. That would charge if the vehicle was revved highly and would keep charging once revved until it was turned off again.

As steve has just said, That one also turned out to be the wrong type alternator.

The older type alternators require a Warning light wire in the other terminal to enegise the alternator to make it charge at low speed, I would think these later alternators would charge ok simply with a Battery feed wire connected. ( I will test one to confirm )

These later alternators only have a wire in the DFM terminal which is an ecu monitoring signal.

You could pull the plug out and use a warning light or test lamp connected between Battery pos and the other terminal in the 2 pin plug of the alternator and see if the light comes on and goes out OK. ( Thats basically how most alternators are tested on a test bench )

Does the car start ok on its own battery power. ?? If not fit a substitute battery.

Have you checked the voltage directly at the alternator body and B+ terminal. ??

H.T.H. Tony.

Thanks for the replies. I haven't checked the gearbox earth but the garage it was in before have actually relocated the engine-battery earth with a second cable? This alternator does have a two pin socket on it but only a one pin connecter from the loom? could this be the connection for the wire thats supposed to excite the diodes on this particular alternator, hence no charge? Could i give this pin a feed and see if it begins to charge or is that a no no! I replaced the battery at the start as it was completley dead so that should be ok, its a bosch bat.
Voltage is the same at the alternator as it is at the Battery.
Thanks again and keep em coming
Also i tried uploading the image but it kept telling me "invalid Format"??

Hi Luke. I have just checked the Tech info on this alternator and it states that this alternator Must be able to excite itself with only a B+ wire connected.

The only problem is that i have tested one with only a B+ connected and it doesn't charge.


To prove if the alternator will work as a standard unit connect a warning light from B+ to the spare terminal. ( not to the DFM terminal thats got a wire in it ) just pull the plug out and use a speaker terminal onto the spade.


Tony

Used a test light connected to battery positive and as soon as you touch either connector on the alternator it starts charging at 14.57v! It continues to charge at this rate with the test light disconnected, until you switch the engine off then back on again and it charges at the original 11.5v until ou touch one of the connectors with the test lead? Does this mean the c\ar has the wrong type alternator?

I would guess so Luke, Just thought, Can you see a part no on that Alternator. ??



p.s i have just retested the alternator and it does cut in at fairly high speed without a D+ wire and the pulley is smaller than normal, so it could work fine on a car.

Tony.

Its UNA1331N, its a universal part or atleast thats what it says on the box, cant see a part no. on the unit??

I cannot get a cross reference for that pat no Luke, But i would think that youve answered the problem, It will be a non genuine alternator possibly not suitable for that application.

funnily enough we have sold one today for an 06 berlingo with only one wire in the plug and that was listed to have a standard alternator fitted so may have a D + wire rather than the DFM terminal.

The days of fitting alternators that look as though they will do the job is coming to an end, I am now getting very wary of what we are supplying, But its difficult when our suppliers usually know less than we do. All they are using is an application list which isn't always correct.

I think in your case, Buying a non gen alternator has caused the garage and the customer a lot of grief and expense. ??


Tony.

Your right there, you have to be very careful what component your fitting now, something that has come back to bite this customer on the derrier, mind you at £345 for a genuine unit it's no surprise a customer is easily pursuaded by a unit that's a third of the price! But you get what you pay for!
Thanks for all the posts, learnt alot!
Luke.