1986 2H 24V woes...about to jump off the deep end. (1 Viewer)

[aaron9252]

Guys,

If you're like me, you REALLY like figuring things out yourself and it feels like a kick to the junk when you get to the point of giving up. Well, when it comes to my 24V 2h, giving up translates to taking it somewhere to be diagnosed which then leads to being kicked square a second time by someone who originally acts like they can diagnose but after hours of 'work', multiple replaced parts, the issue may still exist.

Enough about that potential nightmare so I'll get right to the point. Anyone in the Mooresville/Charlotte area that wouldn't mind offering some time in helping me identify the root cause to my electrical issue on my 60?

I'd be happy to pay in brews but in all seriousness I would pay $ if you could assist.

This is my first and only diesel so I'm learning as I go. Here's basically the issue...

Been dealing with this for a few months. Had an electrical issue where I couldn't figure out if my batteries weren't charging due to bad wiring and grounds or an alternator issue. I sent the alternator off to be rebuilt and while that was being done I checked wiring, found some opportunities, and replaced as necessary. Once I got the alternator back, reinstalled, replaced batteries with new, and she fired right up and charged appropriately!

EXCEPT, I noticed the charge lamp flicker when ignition was turned on. For a split second. It had never done this in the past. For the past two weeks I've been trying to root cause but cannot figure it out. If I leave my cables hooked up, my batteries will be dead by the morning! It's drawing power somehow.

I've retraced my steps a few times but feel like I'm going in circles. Tonight I found that the Charge Light relay in the kick panel clicks when I hook up the positive battery cable to complete the circuit. Not sure if that's the root cause but I posted about that in the diesel section.

Again, hate to ask but Any help would be appreciated!

 

[Rice]

Questions ... have already been through the process of watching current draw on an ammeter while pulling fuses? Also, the alternator service was a rebuild, not a replacement? Was there any mention of diodes in the alternator being tested and confirmed good?

I do not know the layout of the 24V systems but I'm curious about the relay you mention. I would rather doubt a relay was being used as part of the charge indicating system. Have you been able to verify that's what it is?

 

[whitey45]

Check for a draw with an ammeter,this will lead to your problem.

 

[AndrewHadji]

How i like to approach draw is measure continuity between the battery posts and pull fuses until the circuit that is drawing is found. It certainly is frustrating. I had so much extra wiring to get rid of. Im talking tens of feet. Good luck

 

[GLTHFJ60]

How i like to approach draw is measure continuity between the battery posts and pull fuses until the circuit that is drawing is found. It certainly is frustrating. I had so much extra wiring to get rid of. Im talking tens of feet. Good luck

Outside of cleaning grounds, this is the best way to do it.

Alternative is that a battery or the batteries are going bad.

 

[Rice]

Outside of cleaning grounds, this is the best way to do it.

Alternative is that a battery or the batteries are going bad.

I believe original post said new batts.

So yep, time to either measure amp draw or measure continuity.

 

[aaron9252]

Questions ... have already been through the process of watching current draw on an ammeter while pulling fuses? Also, the alternator service was a rebuild, not a replacement? Was there any mention of diodes in the alternator being tested and confirmed good?

I do not know the layout of the 24V systems but I'm curious about the relay you mention. I would rather doubt a relay was being used as part of the charge indicating system. Have you been able to verify that's what it is?

Yes, the alternator was fully rebuilt. Diodes, stator, resistor, bearings, and internal regulator.

The relay is the Charge Light Relay seen in the image below.

I've printed out the FSM and I bought an ammeter via Amazon that will be here tomorrow. So I'll be testing and pulling fuses per everyone's suggestion.

 

[aaron9252]

Pic

 

[aaron9252]

I had a few minutes go check for resistance and was surprised to see this reading out of the gate. Am I doing something wrong? Shows 0.0.

This is an AC ammeter, unfortunately doesn't have DC functionality which is why I ordered another.

 

[slceso]

I'm not trying to talk down, just going on what you've posted so far.

looks like your meter does AC and DC, it has the 2 "V" positions on the selector and is indicated on the meter ratings; straight line DC, sine wave AC.

are you measuring resistance from "-" post to chassis ground on a disconnected battery? what are you trying to figure out there? I would leave the batteries connected and "-" cable connected and isolate "+" fuses, relays, connections to isolate.

For current draw, should be able to connect your clamp around the main "+" cable coming off of the battery (select 2/20A) and measure draw on the battery under various conditions (that meter may not have low enough sensitivity though depending on the magnitude of the current). If it is registering anything with the ignition off, you have a ground on a "+" wire somewhere (unless you have a electronics that always draw for clock, memory, etc).

from your schematic, looks like the charge relay light should be lit anytime your alt is not making [nominal voltage] to charge the battery. That what those zener diodes are doing, preventing current flow through the relay coil until the Vt is high enough to overcome and cause reverse bias. If that light is coming on and off while engine running, your alt may not be making high enough voltage (due to rebuild issue or maybe a component just failed again). I would not suspect that you have a large enough fault to drag down the whole DC system sufficiently to cause the charge relay to pick up, and not have a blown fuse, magic smoke, or sparks somewhere.

with everything connected and engine off, what is your total battery string voltage as read on the meter? now start it and measure again (Alt Vt). post up. good luck! Electrical problems are the devil.

 

[slceso]

Also, if you haven't done it, you should pull your batteries and have them load tested separately. It is not likely, but you could have one with an internal fault causing self discharge or a cracked cell jar allowing discharge to ground.

 

[aaron9252]

Also, if you haven't done it, you should pull your batteries and have them load tested separately. It is not likely, but you could have one with an internal fault causing self discharge or a cracked cell jar allowing discharge to ground.

Yeah, that's a good call on testing the batteries again just to make sure, although they are new.

Also, the ammeter in the pic has DC for volts but not Amps. Dumb. So had to buy another that does both for Amps.

The pic of continuity testing was the positive side of the lower side battery. In hindsight, I should've tested the high side battery. I thought it wouldn't matter since they run in series. I'll check tonight.

 

[slceso]

Also, the ammeter in the pic has DC for volts but not Amps. Dumb. So had to buy another that does both for Amps.

Weird since in their photos they clearly show it being used to measure a DC circuit and there are printed ratings for DC on the clamp, but in the application table it is blanked out for DC.. meh.. Fluke etc.
Etekcity MSR-C600 Digital Clamp Meter, Auto-Ranging Multimeter with Voltage, AC Current, Diode and Resistance Test: Amazon.com: Industrial & Scientific

The pic of continuity testing was the positive side of the lower side battery. In hindsight, I should've tested the high side battery. I thought it wouldn't matter since they run in series. I'll check tonight.

I don't know what the expected resistance reading across a battery cell should be with a DMM, but the internal cell resistance is micro-ohms with something like an Alber cellcorder and IIRC it has to be open circuited. so if you are measuring "+" on low side battery to "-" on high side battery with the intercell connector lifted, seems like there is a hard ground on your high side battery or "+" output cables, or more likely, the voltage present between your two cells is tricking out your DMM since the DMM applies a small voltage to measure resistance. definitely weird. regardless, measuring resistance of an energized circuit to ground with an ohmmeter will likely not give you a meaningful reading (and might damage something).

 

[aaron9252]

Well, thank you guys for the suggestions and commentary around utilizing an ammeter to measure draw.

I have now backed away from the deep end.

First test led to the amperage going down when the Charge fuse was removed.

Since the only real major change was to the alternator, I decided to disconnect one wire at a time and test. After disconnecting the green plug, Amps went down to .04. I knew that was it. I removed the a/c compressor to get to the I/C regulator. Sure as heck two of the wires were connected incorrectly on the regulator that was causing the havoc.

After reviewing the FSM, re-connecting correctly, then putting everything back together and remeasuring, it was back to normal operation!

Thank the Good Lord and of course the help from this group.

She'll be back in full operation tomorrow!

 

[David70FJ40]

I am constantly amazed at the knowledge exhibited by the posters here on MUD and ONSC and their willingness to help. Happy you were able to find the cross up.