Gen 1 Light and Fan

[motormayhem]

When I was driving home tonight I had the heater on full speed as I normally do. Everything was find until the Gen 1 light randomly came on as bright as when the engine is off and the fan shut off. Then light went off and fan came back on. It did it one more time and again fixed itself. I decided to investigate it a little and so with the truck idling I turned on everything, my aux lights, headlights, dash light and noticed that when I turned the fan off and on a few times it would reproduce the problem and sometimes the volt gauge would dramatically drop into the yellow and sometimes it would stay in the green. When I shut the fan switch off it would jump right back into green and shut the gen 1 light off. The alternators are about 2 years old since a rebuild and neither were hot or making funny sounds. When I got home I jiggled the wires on both alts and got the gen 2 light to not come on with the engine off and the ignition on (im guessing that this is just a bad connection and unrelated as it came back on after moving the wires a little more). After that I spent about 5 minutes trying to get the problem to happen again, but it wouldn't do it. I also did notice that when the fan is turned on the volt meter dips just a bit for a second and returns and the gen 1 light dimly lights and stays like that till the fan is turned off, but that has always been the case. The gen 1 light will not come on or get brighter with anything else turned on or off, the fan is the only thing that affects it and would not work when the gen light was bright. What is happening? Oh and belts are tight with about 1/2" of play in both of them when you squeeze them by hand.

 

[68impalass]

most likely your heater fuse is not tight in the holder. the heater blower fuse circuit "turns on" the alternator

 

[choll]

Can you explain the heater blower fuse circuit turns on the alt. The reason I ask is my heater fan is not working and I cant get the front battery to charge even though I get the proper voltage reading at the exciter wires. The alt bench tests ok.

 

[doghead]

The same thing was mentioned recently in this thread. http://www.steelsoldiers.com/cucv/62413-batteries-dying-my-cucv.html

I am not sure why people are saying this, but it seems to be a recurring issue.

Perhaps a diode exists or a capacitor, that is going bad and back feeding one of the two circuits? I really haven't looked too close, since it has never happened to me.


I could see where a short in the fan circuit could cause a large load on Alt 1 and create a problem, but so far I haven't seen where the blower and the alt are tied together(fuses).

It's definitely and issue/mystery to solve

 

[Barrman]

My alt 1 light will glow with the headlights on and the fan on speed 2. The light will almost shine with the fan on 3 or high.

I haven't yet put a meter on the front battery while this is happening. Maybe I can tonight if my Scout meeting gets done fast.

 

[motormayhem]

Im thinking the fuse is the issue at least for me. I pulled it today and it was dried out, old, and the plastic housing was 1/2 melted for some reason. Driving around town today with no fuse in there the truck runs 100% with the meter in the green right on the tick, but without a fuse when I try to turn on the fan the gen1 light instantly illuminates at any fan speed setting, but the batt gauge stays happy. I'll try and look into the reason behind this some time. I'm glad someone knew the issue cause that was probably the last place I would have thought would be causing my problem.

 

[Barrman]

I got to my meeting early and got the volt meter out.

14.40 volts at the front battery with the lights on and engine running.

14.39 at front battery with lights on, engine running and fan on 1 click up.

14.35 volts at front battery with lights on, engine running and fan 2 clicks up.

14.25 volts at front battery with lights, engine running and fan on high.

It was raining pretty hard at the time and I told Colton to just skip the 3rd fan position. Otherwise, I would have gotten it.

From those readings, there really is no reason for the light to be on with the lights and fan on at the same time. The wipers being on with these made no difference on the glow at the different fan speeds.

I will hopefully have time to investigate and figure out what is going on to cause this.

 

[dependable]

As I noted in the other thread, If you remove the blower fuse (it is the highest fuse on fuse pannel), the alt 1 light and alt are disabled. This seems to show the circuits are connected.

 

[TCUCV]

Driving around town today with no fuse in there the truck runs 100% with the meter in the green right on the tick, but without a fuse when I try to turn on the fan the gen1 light instantly illuminates at any fan speed setting, but the batt gauge stays happy.

So in the summer months, taking the fuse would be a simple fix so this problem doesn't drain your batteries?

 

[Jeremiah_Johnson]

Heater blower fuse

I had bought a 1985 M1009 the other day and am currently trying to work out the Gremlins . Very helpful that I own another running ( 85 M1009 ). I noticed that Did not get gen 1 light on start up, but do get gen 2 light. and I got gen 1 light when I turned on heater blower with engine running. I do on the running M1009 get ( both gen 1 & gen 2 ) on start up , using ( the KISS Method ) I checked the fuses and found no bad fuses I checked the Alternator Gen 1 driver side . I got 12 volts at big red Battery wire & 12 volts at red wire on double plug charging wire. But no 12 volt with key on exciter wire, so I looked up fuse block and found location for Heater fuse and double checked fuses .. I found only after looking at my 1st M1009 that I had no fuse in the heater fuse location so I installed a new 20 amp fuse and Bam. one dead Gremlin.. now I get Both gen 1 & 2 lights and working heater blower motor. The Gen 1 exciter wire and the heater blower motor are on the same circuit.. one more Gremlin to fix as I have the right side Blinker light on when Lights are on ( usually means Blown bulb ) but It checks Good even changed bulb so Now I have no running light on passenger side . I believe it to be a broken wire some where . get to that soon..opcorn:

 

[Dr.Jay]

I had the same problem with a customers M1008. The gen 1 lamp illuminating when the heater blower was turned, due to a missing heater fuse. There is no indication where the Gen 1 lamp is grounded in the schematic (TM 9-2320-289-20 Figure-9 ) so i will surmise that this unknown ground is the cause of the problem when the fuse is removed.

On my M1009 the right side tun lamp was on solid when the parking lights were turned on. I found corrosion at the splice on the dark blue wire under the front battery tray for the right front marker / turn signal lamps.

TM 9-2320-289-20
page 866
figure F-10

 

[cucvrus]

Very interesting thread. I was driving the Mule M1009 this AM and when I came from the coffee shop the Gen1 and oil light did not come on when starting. When I started the truck the gen light was on solid. The voltmeter was charging where it is supposed to be. But the fan would not run. It was 47 degrees at 0500 this AM. I needed some heat. Every time I turned the fan switch on the Gen 1 light came of full. I reached up under the dash to the blower switch/plug. It was all tight. I am leaning towards the fuse being loose in the fuse block. I will look when the weather dries out a bit. Anyone have any input? It is an intermittent problem so the fuse may be the problem. Other then that the Mule M1009 never misses a beat. It is cold when you have the rear window rolled up and wide open. It has been cool and rainy here the past several weeks. That is about to change.

 

[cucvrus]

All fuses good. Start truck normal. Glow plug wait light and starts right up at idle no gen 1 light increase RPM's and turn on fan. Gen 1 on steady. When I shut engine off I can not get the gen 1 or the oil light to light. The fan does not work running or in the on position. Weird it charges fine. I will see if fan is locked up and check current to fan motor. I will also check all the grounds. They appear clean. I done nothing out of the ordinary. I am baffled at this time. It must be something easy. I will be away from the computer a few hours. I have work to do. I will report back. vini vidi vinsi.

 

[cucvrus]

Looked a little further. Found nothing. I think it could be the fan switch. I am not ready to remove the cluster. I will attempt to change the switch from below. Done it before. It charges fine and I can drive it like it is for now. Maybe over the weekend I can change the switch. I checked and have no current running to the fan motor when the switch is turned on. I pulled the plug on back of the blower switch and looked at it. It looks fine from the floor looking up and snapped right back in place. Most I see are melted and not able to pull apart and get back together. I had dielectric grease on the plug since I started running this truck. Full report when I find more information.

 

[cucvrus]

Dash out. No current coming to switch. Replaced switch from under side before removing cluster. 2 fuses in second row from bottom of fuse box side by side. No current to them. checked all fusible links under hood. Checked ground on left inner A pillar all good. Any ideas. Still running and charging. No gen 1 light or oil light when I turn key on. Gen 1 light on brightly if fan switch is turned on. I will keep looking. Any ideas? Electrical issues are my weakest link. I also hate working on the fragile clusters and bezels on the dash. Poor dash set up with all the weak plastic parts. Back at it. report back later. Vini Vidi Vinsi

 

[cucvrus]

Mission accomplished. I knew I would find it. It was just a matter of time. With electrical wiring being my weak point I tore into it and I found the problem. That was easy. A test light will tell the truth at all times if it is working. keeping in mind My Mule M1009 is pure stock and I drive it all year round and all spring/summer long with the rear window open. I have been caught in rain and left the door windows down in some severe thunderstorms and water battles. This is how I started the evening after work. And the last 2 pictures is how I finished. back on line and ready for any thing that comes my way. Cost. 3 fuses. I used a points file and cleaned the contacts on the fuse block. The 30 amp on the top was a liar all the time. It tested and lit the light on both legs of the fuse. I removed the bulkhead connector and looked at it. It was still clean and had the dielectric grease I put on it several years back. I checked all my grounds again and tested them. Good. I did find 2 fuses side by side that were warm a few times from dirty connections. I have a circuit breaker wired into my lighting circuit. That eliminated that hot slot in the fuse box. The wiper fuse was hot a few times. I understand that I was in 40 inches of snow for 24 hours straight last year. And the 20 amp hot one I lost track of where that one came from. the culprit was the top fuse for the blower motor it was there and carrying current. It was not sending the current into the wiring harness because of corrosion. Probably all the wash outs and water, snow and ice over the years have caused a minor issue. Nothing bad. I found it and that is all that matters all by myself. The 30 amp at the left / green was the culprit.
I looked round
And I knew there was no turning back (Thunder)
My mind raced
And I thought what could I do (Thunder)
And I knew
There was no help, no help from you (Thunder) I was Thunderstruck. And i fixed it. i hope it helps just 1 person and it was worth the extra effort.

 

[MarcusOReallyus]

A test light will tell the truth at all times if it is working.

Exactly right, Rick. A meter is a necessity, but they can lie to you. If there is corrosion upstream, a meter may show the correct voltage on an unloaded circuit, but put a load on it and that resistor (corrosion) drops that voltage like a rock. A test light will usually put enough load on there to show the problem while a meter will tell you all is well.

 

[PJL]

Just had the same issue on the 1008 here. The Gen 1 light had been flickering on and off while driving. Gen 2 took a long to time to go out. I installed the 2 brand new alternators I had and that cured the Gen 2 issue. But no light on Gen 1. I tested all the fuses with the test light and all were good. But as Rick pointed out the fuses can still pass current but due to burned contacts in the fuse box it wasn't passing current to the lights and the heater fan. And who BTW thought sharing warning lights with the heater was a good idea?

 

[MarcusOReallyus]

And who BTW thought sharing warning lights with the heater was a good idea?

That's not the only idiocy in the electrical system of these beasties. Just cost cutting, I guess. Certainly not good design.

 

[LT67]

Currently having an issue with my Gen 1 circuit. Both alternators rebuilt within the past few months. Voltmeter is only showing 12.26 for the gen 1 alternator. Gen 1 light is not coming on even with a new bulb. The 20amp fuse was bad, so I put in a new fuse. Still no gen 1 light. My heater blower motor was on it's last legs and it stopped working. Is the non functioning blower motor why the gen 1 circuit is not charging properly?

Electrical systems are not my strong point lol