Hi folks,

Mrs B was out in the 2.8CRD 2006 GV yesterday and reported no issues, no dash lights etc. Today she went to go out in it and it would turn over, just clicked.

I tried when I got home and no turn just clicks, so I put the battery charger on for an hour or so and then went to start it and it started, a bit sluggish but started. Then I thought to put a meter onto the battery just to see what the alternator was putting into the battery... 10.6, 10.5, 10.4 falling by the second.

So i switched on the heater, radio, heated seats, rear demister and the voltage dropped to 7.5v and falling, with no lights visible on the heater panel or radio. Turned them all off and it went back to 10.4v

My guess is the alternator dead. The battery was new a couple of months ago, so assume it is the alternator? Is it repairable or is a replacement required? Can I check the alternator output directly or is this indicative enough?

Thanks in advance.

Steve

 

Yep, you've done a perfect test, voltage should be 12-14v whilst running depending on the battery temperature controlling the charge voltage, but 10 and lower when accessories are on indicates alternator failure.
I'm assuming the accessory belt is in place and not slipping, otherwise yes replacement needed.

 

Just had to change my alternator, I went on to the battery and was getting 10.5v so just ordered one.
Reconditioned unit, £91 on Ebay just now, you send yours back. Seller includes a return postage label.

 

Thanks both.

Any guides as to how to replace the alternator - I am guessing I need to remove the tension from the belt...??? and it's not just a rotation of the alternator any more???


Ta

Steve

 

No problem, shouldn't be too bad a job, I've had most of mine off before. You take the tension off the acc belt using the tensioner pulley, take the airbox off (it makes it easier) and you'll see the tensioner about half way down, tricky to get at (I used a long ring spanner) but reach down and hold it around half a turn I think it is which will let you take tension off, then usual few bolts for the alternator.
Also, don't forget to disconnect battery before starting since the wires for alternator obv carry a hefty current so you don't want to short anything!

 

I watched this before doing it. If you're planning changing the glowplugs any time soon, alternator out gives you good access to the most troublesome one.

 

So, ordered the ebay alternator, and fitted it - success. The battery was flat so couldn't start it there and then, so put it on charge overnight.

This morning... 12v on the battery, fired up first time. BUT once it was running the dash lights and dials flickered then went off, as did the radio display. So I put the meter on the battery with the engine running and the meter told me 18v!!!!

The ebay add says: Voltage setting 14.5, so where have the extra volts come from? Any idea or a faulty alternator from ebay - off to work now, so another job for this evening...

Thanks for your help so far,

Steve

 

(Corrected, had the info slightly incorrect there)

The alternator is controlled by the ECM to regulate the voltage using control wires to the alternator which use field windings to regulate the voltage down to the 14.5v or lower required, so check your wires to the alternator as first port of call, I'd not be starting it again in a hurry, need to double check things because over-voltage can cause all sorts of problems with the electrical system, BCM, etc.

I'd try putting the car ignition on (DO NOT START) and see if the dash lights up, dials ready to indicate if it's done permanent damage, but I'd be pointing the finger at the alternator pretty quickly there.

 

Thanks Andy,

The dash lights up and everything seems ok at this stage.

The ebay seller has come back and said: We test our alternators before we send them. From what you are saying it looks like your regulator is faulty so you need to replace it.

Is there a separate regulator on the GV?

I shall check I've not bent the pins in the connector when I get home tonight, otherwise which wires am I checking as no wires were disturbed other than the battery connections and the two connectors on the alternator.

 

No separate regulator, the 'regulation' is done by controlling the field windings of the alternator using those additional wires from the ECM.

So that leaves either the alternator not functioning correctly when the ECM requests it, or the ECM itself. Unfortunately either could be at fault at this stage and I'm unsure how you'd go about testing to prove one or the other.

One thing I'd be avoiding is starting her up until you've made progress, at 18v the battery will be damaged over prolonged use and I'm not sure how much/what damage would be done to the rest of the cars electronics.