Water cooled Alternator

[Henrym3]

Hi guys, long time since I posted but now that I’ve got a problem this is the place to come. As above my alternator is working fine, have a volt meter fitted and getting 13.5v idle 13.8+v at revs. No battery problems but have the battery warning light on permanent. Apart from cleaning earth and using contact cleaner on the connections what other options would you suggest.
2002 4.6is 167k Thanks in advance.


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[Henn28]

Mr. Bentley says, in this order…
1) check all terminals for corrosion and security, and that the drive belt is not slipping b4 testing the alternator.
2) could be an instrument cluster fault. Check that the ground is secured to the stud on cylinder head A. It’s the braided one that grounds the head to the coil stud I think. Who knew.
3) voltage across battery terminals should be ~ 12.6v with key off and between 13.5v and 14.5v with engine running.
4) if no load tester available a quick output test at 2000 rpm with all electrical loads on should read read above 12.6v.

Your alternator may be getting a little weak perhaps at 13.8 (assuming that is at idle)? I’d try the load test and see how it holds up. And check that ground under the left cylinder bank coil cover.

[Henrym3]

Thanks for that, I’ll load test and check earth at head, in 10 years I’ve never seen north of 14v. Definitely not belt, nearly new and tensioner is good. Will get back with what I find.


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[Explorerlyon]

I have the exact same problem, even after having my alternator rebuilt. The 2-wire connector to the alternator seems to be part of the issue. I can remove it, clean it and the light stays off for a while....then comes back on. I wanted to just replace the entire connector but cannot locate one at all.

[80stech]

I think all the connector parts (contacts and housings) are available but a little tricky to look up the part numbers. Also often overlooked is the condition of the alternator pulley.

[Clavurion]

Quote from WDS:

Battery Charge Indicator Lamp

Terminal D+ is replaced by an isolated electronic terminal 61E in alternators with a multifunction controller. The task of this terminal is, on the one hand, to activate the battery charge indicator lamp and, on the other hand, to indicate to the various loads that the alternator is in charge mode.

The battery charge indicator lamp itself is supplied via terminal 15 from the instrument cluster. It comes on when the voltage at terminal 61E is below 1.5 V. The battery charge indicator lamp goes out when the voltage at terminal 61E is above 8 V.

Alternators with a multifunction controller can be recognized by the plug connection of terminal 61E. As a result, the 6 mm threaded stud has been dispensed with.

The indicator lamp lights up when:

Ignition on with engine stationary, alternator does not charge, failure of belt drive, interruption in excitation, controller overvoltage, break in charging cable

The second cable in the plug connection at the alternator is terminal 15 that serves as a reference signal for determining whether the alternator is charging.

Terminal 61E, blue wire, pin 2
Terminal 15 (reference voltage) from fuse F5, green wire, pin 1

[Henrym3]

The full version of the story is that a few days ago I start up and drive off, get about 20 yards and the whole instrument cluster lights up, ABS/DSC, BATTERY LIGHT, ENGINE FAILSAFE , G/BOX GOES TO 5th gear.After initial panic notice my volt meter is at 17v. Naturally assume the regulator has gone south and then fit my spare alternator with new regulator. Spare works fine except for the w/l. Had no issue with w/l prior to fitting the spare alternator.
Checked the earth. Seems good. Load tested and get 12.7v



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[Henrym3]

I see that on the rectifier there are 6 press fit diodes 3+ and 3- sold as part of a repair kit. Unfortunately I don’t know what role they play and if one failed would it cause the problem we’re having. I am though keen to be enlightened and brought out of the dark ages.


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[80stech]

Yes, there often seems to be more to the story! I think you would be best off to get yourself another alternator or have one rebuilt at a reputable shop.

[Henrym3]

Naw, that’s not an option, in 10 years the truck hasn’t been near a dealer or "reputable " shop and isn’t likely to. It’s let me down on the road once when the throttle pedal potentiometer failed which isn’t bad going with 168k on the clock. Even though the alternator is doing fine I’ve stripped the one I took of and fitted a new regulator to it and I’ll put that in at the weekend and see what happens, if the light stays out then at least I know the fault is within the alternator.


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