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  #1  
Old 11-16-2012, 06:43 PM
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Default 2002 Discovery II charging system issues

Hello,

I have a 2002 with an electrical system issue -

Battery warning light on
Alternator not charging
Radio inoperative
Blower inoperative
Power windows inoperative
Probably some other inoperative features I haven't noticed yet.

All fuses in both fuse boxes are intact.

I believe the problem started when I (stupidly) forgot to disconnect the battery when I started the head gasket replacement. While removing the intake manifold bolts I made contact with the alternator power lead (red) with the handle of my ratchet. I assumed I had blown a fuse but am unable to locate any that have blown. I'm guessing that I fried the IDM or BCU. If this is the case, can I get a matched set of modules (ECM, BCU, IDM/fuse box) and replace them without the help of a testbook? As an alternative I was thinking of replacing the IDM/fuse box first. I believe I can introduce this to the vehicle by leaving the key in the run position for five minutes.
The good news is that the vehicle starts and runs much better now with new gaskets and plugs. I even replaced the crankshaft position sensor while I had the head off.
I've had the alternator bench tested and it passed.

Last edited by Marsalad; 11-16-2012 at 07:18 PM. Reason: Spelling
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  #2  
Old 11-17-2012, 10:25 PM
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Update:

I've since noticed that the power seats are inoperative but the power door locks and remote keyless entry are still functional.
The alarm and horn are both still working as well.
I installed another alternator on speculation but that did not fix the problem.
I also added a supplemental ground wire from the alternator to the three-point "earth bar" between the battery and the fuse box. This didn't change anything.
Thankfully the Discovery was purchased as a weekend vehicle, although I didn't expect that to mean I would be driving it for two days and repairing it for the other five.
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  #3  
Old 11-18-2012, 07:17 AM
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It sounds like you may have fried the control module. Make a list of all the electrics that are inoperable and see if they are all controlled by same module. If so, that control module is bad.
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  #4  
Old 11-18-2012, 08:14 AM
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Take a look at the base of the fuse box, you can pull it up and check the integrity of the wiring below. Probably, when you touched the field post, it shorted a link between the battery (+) terminal and the post. I do not think your ECU or alternator are bad.
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  #5  
Old 11-18-2012, 01:54 PM
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I doubt you fried anything..

If you grounded the alternator main output wire - then take a look
at the schematic for the wiring.

You were removing intake manifold bolts.
Therefore, current would run thru the engine steel and to any ground points
on the engine.

I would think - you jostled wiring getting out the lower back head bolts.
The guy who did my heads before me - actually punched in the fire wall.

Check the fuse box is in solid.
Check for fusible links.

Really what you need is to look carefully at the wiring schematic.

Alternator needs field current to charge - I think that is what the little
wire on the alternator does.

I would trace out where that goes to.
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  #6  
Old 11-18-2012, 06:36 PM
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Thanks to all for responding.

I installed another (used) underhood fuse box and inspected the wiring and connectors to the fuse box. I did not see anything burnt or damaged. Unfortunately I still have the same issues.
I did make sure the ground strap from the left cylinder head to the body was properly reconnected when I re-installed the head.
I think my next step may be to remove the upper intake plenum and trace out that small ground wire.
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  #7  
Old 11-18-2012, 07:44 PM
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Get out your test meter and check all the fuse links (bolt in fuses) and the regular fuses in the underhood box. The fuse links are like a main fuse with multiple things on other fuses down stream from it. The largest fuse link (silver strap left of brown cable in attached photo) could have been blown when you touched the ratchet to the alternator cable. That is one reason Rover always tells you to unplug the battery.

If you are testing fuses, do it with an ohm meter if you can unplug them. If you have bolted in ones, unplug one side of the battery, to prevent battery volts from foling the ohm meter. Or use a volt meter, and place it across suspect fuse links. If they are open, and power is hooked up, you'll read 12 volts across the open fuse.
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File Type: pdf d2 fuse box.pdf (401.2 KB, 13 views)
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Workshop/electrical/owners/overhaul/ECU for Discovery, Range Rover, Freelander, LR3, and older models


Cooling System Problems: http://landroverforums.com/forum/gen...verview-51034/
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  #8  
Old 11-18-2012, 08:00 PM
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Savannah,

Thanks for the response. The fuse box currently installed has a 150 amp maxi fuse in place of the silver strap. This was how I bought the vehicle. The other fuse box that was included in the purchase has the strap, which I thought was a "dummy" so when I swapped boxes I swapped the maxi fuse back in. Am I the dummy? When I tested the maxi fuse before swapping fuse boxes I got battery voltage across the fuse with the battery connected. What does that mean?
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Old 11-18-2012, 08:06 PM
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Battery across the fuse would mean fuse is "open". If it was "good", there would only be a very low voltage across it, like tiny fractions of one volt.
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Free download of RAVE and Rover shop & owner manuals (LR3 and older) in pdf: http://landroverforums.com/forum/gen...ing-lr3-57978/
Workshop/electrical/owners/overhaul/ECU for Discovery, Range Rover, Freelander, LR3, and older models


Cooling System Problems: http://landroverforums.com/forum/gen...verview-51034/

Last edited by Savannah Buzz; 11-18-2012 at 08:37 PM.
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  #10  
Old 11-18-2012, 08:34 PM
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Thanks again. I'll install the strap in the morning and see what happens. It didn't realize the strap was a fuse. I've never seen one like that before.
Also, I don't have anything connected at C0601 in your photo. There hasn't been anything attached there as long as I've had the vehicle.

Last edited by Marsalad; 11-18-2012 at 08:38 PM.
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Old 11-18-2012, 08:34 PM
 
 
 
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150, 2002, amp, box, charging, connector, coolant, diagram, disco, discovery, fuse, issue, land, range, rover, system


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