dash lights?

[98Rodeo]

Last time all my dash lights lit up was when I was getting water in the alternator, check the voltage with the car running, might be your issue

[greenwolverine]

Repairing Hitachi Diesel Alternator
(Isuzu Bighorn 4JG2)
This was my first time, so you senior chaps can laugh all you like.
I had the “dash lights staying on” problem that is found in so many Isuzu threads.
Pulled the alt and a sparky id’ed faulty voltage regulator and rectifier/diode assembly.
He supplied the parts and on top of that I asked to upgrade the diodes from 25A to 35A. I also got a new oil seal that fits on the inside of the alt rear cover. It is not pictured in the parts assembly diagram in the Isuzu manual “unit repair” page 6D3-5.
I am following the numbered steps of the Isuzu Bighorn manual and adding my own notes.
Disassembly
1. Undo Vacuum pump (3 Philips screws) and set aside in horizontal position (I don't know how far off centre the vac pump rotor can slide, but it does)

Good idea at this point is to mark the side of the alt with a marking pen to assist with reassembly. It is not possible to assemble it differently but it helps to have a reference mark anyway.
2. Undo the through bolts. Steel-aluminium fusing will have taken place so find a way to undo them snappily. Philips heads are a pain and I had to saw a groove into one to get a flat-head screwdriver to work. Some people talk of heating the housing but I didn’t have to go there.
3. Don’t bother with steps 3-11 in the manual if you have an electrical problem. They have nothing to do with the alt coming apart. My bearings were fine.
Once the through bolts are out the alt must now come apart into sections. This is scary for the beginner because it doesn’t seem to want to come apart. I undid the rear cover assembly nuts (see 13 below) and with a bit of coaxing and after some anxious moments had the alt into its separate bits (2 housings, rotor and stator+diode). Bashing the shaft with a piece of soft wood while holding the rear housing did the trick.
13. To remind myself that the terminal bolt has insulation washers above and below, I marked it on the housing with my marker pen.
15. I knew that my diode was knackered anyway so I merrily soldered off the three stator leads with no concern for heat transfer to the diodes.
16. Removing the regulator from the diode was a bit scary because there seemed a bewildering array of parts to desolder, as well as a little black box beneath the round plug socket not mentioned in the manual. (condenser?)
What I advise is to make copious notes of what protrusions are found on the left of the black box, and on the right of the black box; to which parts are the three extensions of the connecting plate (1 arrow on p. 11) soldered; what touched what, and what was isolated from what.
I made drawings too, and when resoldering I could put check marks next to my notes when checking for correct matching. Taking pics helps too but I ended up not having to look at them.
In my case the brass rivet at the “terminal plate” in the drawing needed to be drilled out (2 on p.11 step 15) because the replacement diode assembly did not have one. I bolted it onto the new one with the bolt head upmost because eventually there is very little clearance between it and the alt cover and a short would cook the diodes. I used loctite for good measure.
Reassembly
Solder everything together as the parts stack up, and check off the completed joints on your notes.
Now it’s time to solder the three stator leads into place on the new diode assembly. I was told not to panic about getting heat into the diodes since the plates were fairly far from the diodes themselves. But I soldered as fast as I could anyway, since the manual warns against heat getting into the diodes (step 14 on p.11).
Fitting everything together.
Here’s where the fun begins and you may lose a few pounds in twenty minutes.
Tap out the oil seal (I used a long 14mm socket and a hammer)
Tap in a new seal using the back end of a larger socket approximating the diameter of the seal.
Polish the slip ring surfaces with 600 paper (p7 step 1)
I imagine there are two tried and tested ways of holding back the brushes in fully compressed position. Being a novice I tried the third way which is guaranteed to break off the brushes. If you do snap them off, don’t commit hara-kiri or buy another regulator. Strip the motor out of the family vacuum-cleaner or any brush operated appliance bought at the local Salvation Army store, remove its brushes and trim them down to fit (make jigs for accurate cutting and use a sharp chisel). Their copper flex leads can be soldered into place where the others used to be. Solder a thin copper wire to the leads to pull threm through the holes.
A. The Bicycle Spoke method (not tried)
Bolt the diode assembly+regulator+stator to the rear cover. To hold the brushes back, I am told that you can poke a bicycle spoke through a hole in the rear cover while you fit the bearing and slip rings into the recess, and release the spoke when everything is flush. But be daring and try this:
B. The Not-bicycle spoke method.
Park the rotor and front cover on the bench. It rests nicely on the pulley. Now gently slide the stator + diode + regulator over the rotor by holding the brushes back with a thin metal ruler until the bearing and slip rings are all the way through. Tap the stator coil housing down into the front cover using the end of a very soft plank and a mallet. This is where that stripe marking matching surfaces comes in handy.
C. Gently guide the rear cover into place, making sure that the terminal bolt has its isolating washer on the inside of the cover!
Tap the covers together and you will find that enough of the diode and regulator bolts protrude for the rear cover nuts to be tightened and for everything to be drawn into position.
D. Tighten up the 4 through-bolts to spec and refit the vacuum pump. Replace the o-ring if you find that it has gone hard.

When the dash lights went off with a loud click of the relay I was euphoric. It took an hour or so for my remanufactured, hand-fitted brushes to get worn in and once they did the voltage went up to 14 on the road.

Note on charge relays: I have always found that your friendly wrecker will let you take handfuls of fuses and relays without charging too much. Isuzu rodeos are quite popular locally and they have the same ones.

[4x4SWANNY]

Pretty good job there......You only need to desolder the rectifier off the stator and the brush holder/regulator unit..
And then just desolder the volt reg..Using a air gun to blow away solder .. New voltreg ie the BSR LFE are cheap 33 dollars i think for the one i bought a few weeks ago. And the bicycle spoke method of reasembly is the best and correct way..as told to me by a alt reconditioner..Oh and new brushes from a auto electrician are about 7 dollars a pair..
I would suggest getting new ones as the wire to solder them back into brush retainer is alot longer and easier to feed through the hole..