First time Humvee owner, lifetime admirer w/ a Q...

[OrangeElvis]

Just bought an M1097A2 w/ less than 14k miles on odometer (seems in good shape, so may be accurate) and have changed oil, flushed radiator and changed out temp gusge that was reading hotter than reality

I bought two new Hawker batteries for 24 V serial and intend to use batteries (still fairly new/lightly used) that previous owner had in the passenger rear compartment in parallel for 12V use.

Current generator is not charging batteries so either regulator or generator are bad. Either way, I bought a new 400 amp monster w/ dual voltage regulator for a song that I couldn't pass up. It is SUPPOSED to be Humvee compatible with conversion kit.

I am having electrical issues, other than non-charging. My brake lights and blinkers do not work. Headlights and running lights are fine. No codes. Blinker, guage lights both have periodic flickering and blinker sometimes works but mostly just lights up solid when I try to turn right/left (no effect on turn lights) or doesn't light at all.

Thoughts?

 

[TOBASH]

Few things.

First... Welcome!



Pics of the alternator will answer tons of questions.

Brakes, not breaks.

400amp is overkill and requires special brackets. What is in vehicle now? Have you tested it? My friend and fellow member Eric aka Hummer H1 routinely modifies these rigs to accept GM alternators. I would stay with 200 dual voltage unit prior to making any change unless it is damaged. If the belts are torn then you also have an answer.

Have you checked wires for continuity, cleaned leads and plugs and then coated with dielectric grease? Flasher and brake light leads and the rear of the directional signal control should be checked and are known to corrode.

The frame IS NOT GROUND! These vehicles have separate ground wires.

Have you check all lightbulbs to ensure they are good?

Have you cleaned and properly secured the alternator wires and battery cables to rule out a reason for no-charge status?

 

[HoveringHMMWV]

And welcome to SteelSoldiers. I still share your excitement. Love MV’s.

 

[Mogman]

Welcome to the SS forums!!!

The reason you got the 400A alt cheap is because just about everyone that has one wants to git rid of it and for good reason, they are hard to keep mounted because they are SO heavy, they make working on the truck even harder and they have a bad habit of destroying the wire harness.

Download the TMs available here and study the schematics and clean/check all the ground points, that will go along way to fixing many of your electrical problems.

Make sure to check/change all the fluids including the geared hubs, inspect the half shafts for deteriorated boots and loose CV joint bolts.

There are tons of folks here ready to help so do not hesitate to ask.

There are no stupid questions only the possibility of stupid answers!!!

And as said before please post some pictures!!!!!!!!

 

[OrangeElvis]

Welcome to the SS forums!!!

The reason you got the 400A alt cheap is because just about everyone that has one wants to git rid of it and for good reason, they are hard to keep mounted because they are SO heavy, they make working on the truck even harder and they have a bad habit of destroying the wire harness.

Download the TMs available here and study the schematics and clean/check all the ground points, that will go along way to fixing many of your electrical problems.

Make sure to check/change all the fluids including the geared hubs, inspect the half shafts for deteriorated boots and loose CV joint bolts.

There are tons of folks here ready to help so do not hesitate to ask.

There are no stupid questions only the possibility of stupid answers!!!

And as said before please post some pictures!!!!!!!!

Thank you - I have lots of fun tinkering to do and I have read the reviews of the monster generator and understand the drawbacks. I just couldn't pass up the price for less than half of a 200 amp, but accept I may end up regretting my decision

My very first electrical attempted remedy was new ground harness. Then I cleaned and retightened all grounds. I will check relay behind the instrument panel next. Just never done that before so a bit unsure of how to do it, but will keep reading and studying online.

And here is pics of my new monster baby.

 

[OrangeElvis]

Few things.

First... Welcome!



Pics of the alternator will answer tons of questions.

Brakes, not breaks.

400amp is overkill and requires special brackets. What is in vehicle now? Have you tested it? My friend and fellow member Eric aka Hummer H1 routinely modifies these rigs to accept GM alternators. I would stay with 200 dual voltage unit prior to making any change unless it is damaged. If the belts are torn then you also have an answer.

Have you checked wires for continuity, cleaned leads and plugs and then coated with dielectric grease? Flasher and brake light leads and the rear of the directional signal control should be checked and are known to corrode.

The frame IS NOT GROUND! These vehicles have separate ground wires.

Have you check all lightbulbs to ensure they are good?

Have you cleaned and properly secured the alternator wires and battery cables to rule out a reason for no-charge status?

Thank you for all the great info!

Currently have a 200 amp dual voltage. I am 50+ yr old newbie to all this as I have been a "shade waiting room" mechanic most of my life, having only changed my own oil and tires. Reading a lot and watching all the YouTube videos I can find, but still a little trepidatous that I don't know what I don't know (I already got into trouble not knowing the significance of "upper" and "lower" batteries and the 12V power lines - blinker problem pre-existed my changing of batteries, though).

I cleaned all the contacts when installing the grounding harness and still had a 13V parasitic draw. Checked starter, generator, smart box and transmission module. Still have draw after each was disconnected. Pulled a glow plug and while it was starting to get smoked, it wasn't bad (will replace them all soon, though). What else can pull that kind of draw? Going back to generator, did I miss a ground besides that big weaved metal "strap"? Seems that might explain a few things.

Also, it seems previous owner replaced most bulbs with LED. If I need to go back to OEM, where do I get 24V bulbs?

I am unsure how to properly check generator & regulator for failure, but that is my project today, along with checking relay behind instrument panel. My only diagnostic device is a multimeter that I learning to use: INNOVA 3320 Auto-Ranging Digital Multimeter, Red & Black https://a.co/d/aMSY1ko

I will add pics of alternator and anything else you need once it gets light outside.

Thanks in advance for the input and advice!

 

[ODAddict]

Bulbs--i just received a supply of 24v bulbs--two different types--from an Amazon retailer. Ten bulbs for about ten bucks. This is a significant savings from the usual suppliers (who, of course, must maintain their own inventory).

Just search by the bulb number.

 

[Mullaney]

Just bought an M1097A2 w/ less than 14k miles on odometer (seems in good shape, so may be accurate) and have changed oil, flushed radiator and changed out temp gusge that was reading hotter than reality

I bought two new Hawker batteries for 24 V serial and intend to use batteries (still fairly new/lightly used) that previous owner had in the passenger rear compartment in parallel for 12V use.

Current generator is not charging batteries so either regulator or generator are bad. Either way, I bought a new 400 amp monster w/ dual voltage regulator for a song that I couldn't pass up. It is SUPPOSED to be Humvee compatible with conversion kit.

I am having electrical issues, other than non-charging. My brake lights and blinkers do not work. Headlights and running lights are fine. No codes. Blinker, guage lights both have periodic flickering and blinker sometimes works but mostly just lights up solid when I try to turn right/left (no effect on turn lights) or doesn't light at all.

Thoughts?

.
Like @TOBASH mentioned in the very first reply, the frame is not the ground for lighting (or anything else) on the HMMWV. The "grounding kit" can cause you more trouble than you already have by creating a ground loop. You should start with removing each connector and wire brushing the contacts, then apply some anti-oxidant paste. That will take you several DAYS to do. You also need to verify that you have known good bulbs in your light fixtures. Don't forget to use anti-ox paste in those connectors as well. Maybe buy some new bulbs...

Thanks for the pictures - and Welcome to the Outfit!

 

[OrangeElvis]

Bulbs--i just received a supply of 24v bulbs--two different types--from an Amazon retailer. Ten bulbs for about ten bucks. This is a significant savings from the usual suppliers (who, of course, must maintain their own inventory).

Just search by the bulb number.

I don't have original bulbs to find number - and the "-20" maintenance manual I ordered three weeks ago still hasn't arrived... I have downloaded the big manuals, but finding anything on those has been a struggle.

On that note, where can I find a cable code number decoder? Is there such a thing or am I just going to need to ride the manual learning curve?

 

[OrangeElvis]

While I wait for daylight, here is eBay picture of the 400 amp generator I purchased...

 

[OrangeElvis]

.
Like @TOBASH mentioned in the very first reply, the frame is not the ground for lighting (or anything else) on the HMMWV. The "grounding kit" can cause you more trouble than you already have by creating a ground loop. You should start with removing each connector and wire brushing the contacts, then apply some anti-oxidant paste. That will take you several DAYS to do. You also need to verify that you have known good bulbs in your light fixtures. Don't forget to use anti-ox paste in those connectors as well. Maybe buy some new bulbs...

Thanks for the pictures - and Welcome to the Outfit!

To be clear, I did this on all the grounding posts for harness but it didn't take days, so perhaps you mean ALL the contacts for my lights, too?

 

[Mullaney]

I don't have original bulbs to find number - and the "-20" maintenance manual I ordered three weeks ago still hasn't arrived... I have downloaded the big manuals, but finding anything on those has been a struggle.

On that note, where can I find a cable code number decoder? Is there such a thing or am I just going to need to ride the manual learning curve?

.
Generally speaking, there should be a wiring diagram.
Better yet, here is a list of Wire Numbers. (See Attached)

 

[OrangeElvis]

.
Generally speaking, there should be a wiring diagram.
Better yet, here is a list of Wire Numbers. (See Attached)

Thank you! I actually ran across the wiring schematic (I think mine is FO-5):

However, when I look at it I feel very dumb, lol. My background is finance (if you ever need investing advice, I am you guy, lol - I am retired from that life, so I am not hunting for business) so I have a steep learning curve, but have found this forum to be a wealth of information.. I read a lot before posting my question, as I don't want to wear you guys out.

 

[Jinx]

Welcome to the site! I've found these trucks much easier to work on than a modern vehicle with all of its computers and emissions equipment. Plus there are TM's a plenty to help with diagnosis and repairs.

My biggest issue so far has been finding the correct TM in a timely fashion. But that's more of a person problem than a TM problem. lol

 

[OrangeElvis]

Welcome to the site! I've found these trucks much easier to work on than a modern vehicle with all of its computers and emissions equipment. Plus there are TM's a plenty to help with diagnosis and repairs.

My biggest issue so far has been finding the correct TM in a timely fashion. But that's more of a person problem than a TM problem. lol

Yeah, that was my hope. I mean they are supposed to be maintained by 18 yr olds in combat situations... I am not intuitive with machines, but I can learn!

 

[86humv]

Thank you for all the great info!

Currently have a 200 amp dual voltage. I am 50+ yr old newbie to all this as I have been a "shade waiting room" mechanic most of my life, having only changed my own oil and tires. Reading a lot and watching all the YouTube videos I can find, but still a little trepidatous that I don't know what I don't know (I already got into trouble not knowing the significance of "upper" and "lower" batteries and the 12V power lines - blinker problem pre-existed my changing of batteries, though).

I cleaned all the contacts when installing the grounding harness and still had a 13V parasitic draw. Checked starter, generator, smart box and transmission module. Still have draw after each was disconnected. Pulled a glow plug and while it was starting to get smoked, it wasn't bad (will replace them all soon, though). What else can pull that kind of draw? Going back to generator, did I miss a ground besides that big weaved metal "strap"? Seems that might explain a few things.

Also, it seems previous owner replaced most bulbs with LED. If I need to go back to OEM, where do I get 24V bulbs?

I am unsure how to properly check generator & regulator for failure, but that is my project today, along with checking relay behind instrument panel. My only diagnostic device is a multimeter that I learning to use: INNOVA 3320 Auto-Ranging Digital Multimeter, Red & Black https://a.co/d/aMSY1ko

I will add pics of alternator and anything else you need once it gets light outside.

Thanks in advance for the input and advice!

...
There's no relays behind instrument panel...only circuit breakers.
That 1097A2 has a relay behind battery box inside of panel which is 24v activated and routes 12v to trans computer...relays do stick on sometimes
with Ignition turned off.
Trans light forward of shifter turns on when ignition is turned on....and should shut off when truck is started or shut off.
If light stays on when Ignition is off...relay is sticking on.
What color is label and box under dash.....Start box ?

 

[Retiredwarhorses]

No one, and I mean no one installs a 400amp on purpose….at least not if they have a 200amp already.
I’ve never replaced a 200amp due to failure, the regulators fail, but I’ve never had to replace the core.
400amp? I’ve had stacks of failed generators cores along with regulators…add to that the damage done to engine heads
and body harnesses and other close by wiring…no thank you.
For those who know what to look for, how to work on these units and understand the shortcomings of that generator? No problem…for those that do not? No sir….
also, you will now need a new Generator/PS mounting bracket, mounting bolt and rear support to install it.

 

[TOBASH]

Throw out the 400 amp or sell it to the people with six ton and LMTV. They have their own forums here on SteelSoldiers. Listen to RetiredWarHorses/RWH.

You need to ground the individual lights. You need to open them up and find the contacts and wires clean them and check them. You need to check to see if current is flowing through the circuit. You need to check the actual blinker assembly itself, which controls the flashers and if I recall correctly also controls brake lights. You need to check the brake light switch.

Checking alternator is easy. Start the vehicle, and place a meter on positive and negative leads, and if it reads anywhere between 26 and 29 V, you have a functioning alternator. Then you can check the 12 V leads to see if they are working also in a similar manner. If not try buying a new regulator. Check to see if yours is part Neihoff number N3135. Number is on regulator. Choose whatever number you have and buy one from Kascar.

Placing that 400 amp monstrosity will be a mistake causing your own undoing. People tear those alternators out. They are not rushing to install them.

That grounding kit is a disaster. What you need to do is clean all your wires. Starting from the batteries on the alternator and working peripherally. Mullaney has written about this above, and he is 100% correct.

 

[OrangeElvis]

No one, and I mean no one installs a 400amp on purpose….at least not if they have a 200amp already.
I’ve never replaced a 200amp due to failure, the regulators fail, but I’ve never had to replace the core.
400amp? I’ve had stacks of failed generators cores along with regulators…add to that the damage done to engine heads
and body harnesses and other close by wiring…no thank you.
For those who know what to look for, how to work on these units and understand the shortcomings of that generator? No problem…for those that do not? No sir….
also, you will now need a new Generator/PS mounting bracket, mounting bolt and rear support to install it.

Yeah - I am hoping it is not my 200 amp generator. I wanted the 400 as backup in case the 200 amp is toast. I am glad to hear that the 200 amp generators going bad isn't common. I literally got it for a fraction of new 200's with regulators but I hear you. I low balled the seller and he took me up on it, lol. It still in the original box sitting in my garage. I don't plan to push the generators hard in any case. I have 24V A/C and winch in my plans, but with 200 amps, I should be good.

The previous owner swapped mechanical fan for 12V electric and I bought a "pusher" dual fan that I will install once I figure out the generator/regulator issue. That is going to be around 37 amps if/when both fans are blowing - which is why I want two 12V batteries in parallel to power those and any accessories I add down the line.

 

[OrangeElvis]

Throw out the 400 amp or sell it to the people with six ton and LMTV. They have their own forums here on SteelSoldiers. Listen to RetiredWarHorses/RWH.

You need to ground the individual lights. You need to open them up and find the contacts and wires clean them and check them. You need to check to see if current is flowing through the circuit. You need to check the actual blinker assembly itself, which controls the flashers and if I recall correctly also controls brake lights. You need to check the brake light switch.

Checking alternator is easy. Start the vehicle, and place a meter on positive and negative leads, and if it reads anywhere between 26 and 29 V, you have a functioning alternator. Then you can check the 12 V leads to see if they are working also in a similar manner. If not try buying a new regulator. Check to see if yours is part Neihoff number N3135. Number is on regulator. Choose whatever number you have and buy one from Kascar.

Placing that 400 amp monstrosity will be a mistake causing your own undoing. People tear those alternators out. They are not rushing to install them.

That grounding kit is a disaster. What you need to do is clean all your wires. Starting from the batteries on the alternator and working peripherally. Mullaney has written about this above, and he is 100% correct.

Thank you for the help! As promised, here is a picture of my current installed generator/regulator: