Not yet. I'm curious what that picture shows and if that really was causing your problem.
Rudi
BJ42 - Electrical system woes (24v)
- Thread starter Snow Peak
- Start date
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Not yet. I'm curious what that picture shows and if that really was causing your problem.
Rudi
- Thread starter
- #42
@bj40green
Hey Rudi,
So looks like the charging issue has gone away. Turns out the ground wire between the alternator and voltage regulator fried. I will post pictures of that once I get back into town.
I've been having an issue with my vacuum pump; I made a thread for it here
I know have a new problem (potentially). I swapped in that used alternator to see if it would solve the noise issue; it didn't. Today I decided to swap in my old alternator (as I just borrowed the other one and it needs to be returned), and after checking the voltage after I installed it, it seems really high.
From the alternator +B stud to the low side battery I am getting between 29.8 and 30.11v at idle with no load. Also at idle, the low side battery is sitting at 15.41v and the high side at 14.76v. Does that seem way to high? With the throttle pulled, the voltage goes up to 31.2v.
I forgot to check the voltage before swapping alternators but the shop said that the "new" one was charging just fine, so I just left it at that.
Hey Rudi,
So looks like the charging issue has gone away. Turns out the ground wire between the alternator and voltage regulator fried. I will post pictures of that once I get back into town.
I've been having an issue with my vacuum pump; I made a thread for it here
I know have a new problem (potentially). I swapped in that used alternator to see if it would solve the noise issue; it didn't. Today I decided to swap in my old alternator (as I just borrowed the other one and it needs to be returned), and after checking the voltage after I installed it, it seems really high.
From the alternator +B stud to the low side battery I am getting between 29.8 and 30.11v at idle with no load. Also at idle, the low side battery is sitting at 15.41v and the high side at 14.76v. Does that seem way to high? With the throttle pulled, the voltage goes up to 31.2v.
I forgot to check the voltage before swapping alternators but the shop said that the "new" one was charging just fine, so I just left it at that.
If the ground wire between the alt and the VR is fried....... it means that you have a ground problem between alt, engine, frame, battery.
The (negative) current found it's way through that alt/VR wire. If that ground problem is still there it can cause the VR to react strange.
Check your ground straps. A fast way to check is using your jumper cable. Hook up the black lead to the alt housing and the other side to the negative battery stud. Do you still have those "strange" voltages? Remember: Max voltage is 28.8V.
TIP: check the batteries in your DMM because getting "between 29.8 and 30.11V at idle with no load" is not good and can be caused by low/bad batteries in your DMM.
Rudi
The (negative) current found it's way through that alt/VR wire. If that ground problem is still there it can cause the VR to react strange.
Check your ground straps. A fast way to check is using your jumper cable. Hook up the black lead to the alt housing and the other side to the negative battery stud. Do you still have those "strange" voltages? Remember: Max voltage is 28.8V.
TIP: check the batteries in your DMM because getting "between 29.8 and 30.11V at idle with no load" is not good and can be caused by low/bad batteries in your DMM.
Rudi
- Thread starter
- #44
Hi Rudi,
I did have an issue with a bad ground between the alt and battery a long time ago which looks like was the cause for the ground between the alt and VR to fry. New grounds have been added and the ground between the alt and VR fixed (opened up harness to find the fried wire). I got the truck back from the shop about 2 weeks ago and it was charging normally.
Only since trying to find the source of vacuum pump noise have a noticed that the alt is now over charging.
I grabbed my brothers DMM and went out and checked again. At idle the voltage reading from the +B stud and negative battery terminal sits at 30.8v.
I did have an issue with a bad ground between the alt and battery a long time ago which looks like was the cause for the ground between the alt and VR to fry. New grounds have been added and the ground between the alt and VR fixed (opened up harness to find the fried wire). I got the truck back from the shop about 2 weeks ago and it was charging normally.
Only since trying to find the source of vacuum pump noise have a noticed that the alt is now over charging.
I grabbed my brothers DMM and went out and checked again. At idle the voltage reading from the +B stud and negative battery terminal sits at 30.8v.
It's too high but that you already know. Did you do the jumper cable test?
Take your DMM and connect the black lead to the Negative battery stud.
Take the red lead and check for voltage on the VR housing, the firewall, frame, engine block and alternator housing.
All readings should be 0 (zero) Volt.
Rudi
Take your DMM and connect the black lead to the Negative battery stud.
Take the red lead and check for voltage on the VR housing, the firewall, frame, engine block and alternator housing.
All readings should be 0 (zero) Volt.
Rudi
- Thread starter
- #46
Hi Rudi,
I checked the voltages at the locations that you listed. All read zero volts.
I noticed that when I first started the truck up, the voltage from the +B stud to the battery was 24.6V then steadily increased to 30.8V where it now stops and stays at.
I checked the voltages at the locations that you listed. All read zero volts.
I noticed that when I first started the truck up, the voltage from the +B stud to the battery was 24.6V then steadily increased to 30.8V where it now stops and stays at.
OK, so 30.8 at idle. What voltage when you rev it up?
Actually it doesn't matter, something is wrong.
Disconnect the VR and check the voltages again at idle ad rev up.
Rudi
Actually it doesn't matter, something is wrong.
Disconnect the VR and check the voltages again at idle ad rev up.
Rudi
- Thread starter
- #48
I checked out the voltages with the VR disconnected.
At idle: 25.6v
Rev'd up (doesn't matter how much): 25.6V - stays the same as if it's still at idle.
EDIT: When I re-plug the VR back in the voltage (+B stud to negative battery), will steadily raise back up to 30.8v.
At idle: 25.6v
Rev'd up (doesn't matter how much): 25.6V - stays the same as if it's still at idle.
EDIT: When I re-plug the VR back in the voltage (+B stud to negative battery), will steadily raise back up to 30.8v.
If the VR is disconnected, the alternator is not activated.
It seems that the alternator is charging when the VR is out of the loop.
Hmmmmm, you have a nice one over there. Time to figure out why the F terminal on the alt is getting voltage.
If not then the alternator has an internal short.
Rudi
It seems that the alternator is charging when the VR is out of the loop.
Hmmmmm, you have a nice one over there. Time to figure out why the F terminal on the alt is getting voltage.
If not then the alternator has an internal short.
Rudi
I think I was a bit too fast..... Your batteries are fully charged and you'll see the battery voltage on the +B stud on the alternator.
Disconnect the VR and start engine. What is the voltage?
Turn on your headlights. What is the voltage? Voltage should drop after a few minutes to 24V or lower.
Another way to test it, is to disconnect the +B wire on the alt. Be careful! That wire is +24V from the batteries.
Start engine. There should be no voltage on the +B stud on the alt.
Rudi
Disconnect the VR and start engine. What is the voltage?
Turn on your headlights. What is the voltage? Voltage should drop after a few minutes to 24V or lower.
Another way to test it, is to disconnect the +B wire on the alt. Be careful! That wire is +24V from the batteries.
Start engine. There should be no voltage on the +B stud on the alt.
Rudi
- Thread starter
- #51
Hi Rudi,
Back when I tested the voltage with the VR disconnected (for post #48), I initially disconnected the VR first then started the engine, it didn't want to start though. It just cranked over a few times until I turned the key back off. I reconnected the VR and she fired right up afterwards. I honestly did not crank it for very long though as it always fires right up nearly instantly. Do the glow plugs not glow if the VR is disconnected? Might be the reason it did not start right away as it was a "cold" start.
I'll be heading back home tomorrow morning (340km drive). I'm hoping that driving that long of a distance with that high of a voltage output won't do damage. Maybe running with my headlights on and having the heater on would be a good idea? I won't have time to do anymore trouble shooting tomorrow as I'll be leaving early
I've said it before but Rudi, I really really appreciate all your help!!
Back when I tested the voltage with the VR disconnected (for post #48), I initially disconnected the VR first then started the engine, it didn't want to start though. It just cranked over a few times until I turned the key back off. I reconnected the VR and she fired right up afterwards. I honestly did not crank it for very long though as it always fires right up nearly instantly. Do the glow plugs not glow if the VR is disconnected? Might be the reason it did not start right away as it was a "cold" start.
I'll be heading back home tomorrow morning (340km drive). I'm hoping that driving that long of a distance with that high of a voltage output won't do damage. Maybe running with my headlights on and having the heater on would be a good idea? I won't have time to do anymore trouble shooting tomorrow as I'll be leaving early
I've said it before but Rudi, I really really appreciate all your help!!
My mechanic was talking to the air plane mech at the airport and he said he could get 24v VR without a problem. I had mine rebuilt but it might be worth looking into. Anyone else tried one made for a plane? Jim
Airplanes, boats, trucks above 3.5 tons, heavy machinery, they all use 24V systems.
Rudi
Rudi
I had a somewhat similar issue with my 42. Every few days it would be totally dead in the morning. It ended up being the fuse block. I can't remeber off hand which fuse it is but I took it out and used a Dremel tool with grinding wheel and to get it to clean metal. I crimped down on the fuse block ends so you had to put a little pressure to get the fuse in there. I haven't had a problem since. Also their is a pigtail coming out of the voltage regulator you can use for testing to see your voltage. It is further down the wiring line so depending on what you get there for voltage, you know you're good to that point. I wasn't seeing the voltage there until I cleaned up the fuse block. Hope some of this helps.