[Q] Wait Light - ground switched?

[FlameRed]

Hello once again. I tried searching. I beg the collective for some more of your fine advice to help me avoid wasting tons of $

Before I upgraded to a 200 AMP generator, the Wait Light did not light for the last couple months. I would wait a minute after turning to run and the truck would start normally. I added the 2nd 12V lead to the battery from the 200 AMP generator in addition I installed the new 24 cable supplied in the kit.

So now I am looking at the wait light. I tested the original wait light with a separate 24 volt supply and it was burned out. So I replaced the wait light and the new one lights with my test 24 source. But when I installed the new wait light it would not come on. Seems like the plus lead is hot with ignition on and the ground is switched by the PCB? There is infinite resistance on the ground lead to the light. If I temp ground that negative lead to the installed new light, it lights.

So does the PCB switch the wait light on via ground?

FYI I have installed a LAU Distribution Box, NSN 6110-01-446-7126, which I do see are no longer available anymore.

I searched for some business that "rebuilds" these but I am not finding one? Seems like it could be a lucrative business.

So which PCB is the go2 one if I have to get a new one? Seems the Nartron S3 Smart Glow Plug Controller Protective Box at the "bargain" price of $700 is the cheapest. Is this ok for a '92 M998 NA 6.2. I guess I should replace the glow plugs at the same time?



The officer I purchased the M998 from replaced all the glow plugs and PCB before he sold it to me, well according to him anyway. I guess he replaced it with something old (used) he had laying around.

I do NOT have a spare PCB, and seeing they want about $1K for one I don't want to buy one unless I am absolutely positive and not just through extremely expensive parts at it

Please give me your advice on how to proceed. Thanks in advance!

 

[Mogman]

The wait light has a #27 (F) wire, all #27 wires are instrument feed so yes it will be hot any time the run switch is on and the PCB grounds the other lead to turn on the light.

 

[Milcommoguy]

Hello once again. I tried searching. I beg the collective for some more of your fine advice to help me avoid wasting tons of $

Before I upgraded to a 200 AMP generator, the Wait Light did not light for the last couple months. I would wait a minute after turning to run and the truck would start normally. I added the 2nd 12V lead to the battery from the 200 AMP generator in addition I installed the new 24 cable supplied in the kit.




A little help from the nose bleed section..... That box is dinosaur old . Uses a separate glow plug connector in the engine bay. Two on top, yes?

All controllers (boxes) provide a ground (logic low) to illuminate the WAIT led , so you're right there.

Might be time to move forward 30 years... Just saying. Any major parts on the HumV are going to cost close $1K... IP, alternator, starter, a hub, doors, you name it.... $1000 buck , includes tax, license, dealer prep, shipping and handling fees.

Ask me how I know, CAMO

 

[FlameRed]

Uses a separate glow plug connector in the engine bay. Two on top, yes?

Yes, I always wondered why I saw a spare plug dangling underneath each glow plug. So now I know why.

 

[Milcommoguy]

A little help from the nose bleed section..... That box is dinosaur old . Uses a separate glow plug connector in the engine bay. Two on top, yes?

All controllers (boxes) provide a ground (logic low) to illuminate the WAIT led , so you're right there.

Might be time to move forward 30 years... Just saying. Any major parts on the HumV are going to cost close $1K... IP, alternator, starter, a hub, doors, you name it.... $1000 buck , includes tax, license, dealer prep, shipping and handling fees.

Ask me how I know, CAMO

 

[Retiredwarhorses]

The LAU PCB is the box that would start Hmmwv’s on there own and burn to the ground…that box is a big “NO GO”

 

[Retiredwarhorses]

May I add, the S3 EESS is the only authorized start box used in the hmmwv By the military ALL other versions are EOL.
Either Narton or KDS manufactured.

 

[Milcommoguy]

AND to add... The only thing good about the LAU box is when we scrap them getting 37 cents more for the nice aluminium deep drawn box and heat sink.

Still junk, CAMO

Not the one you want

 

[FlameRed]

Not the one you want View attachment 910283

Oh boy, now I am really confused. Mine has two harness connectors on the engine side as pictured above. All the pictures I see of the NARTRON or the KDS S3 have only one connector on the engine side

So if I use a NARTRON or KDS S3, or even Camotek - what the deal with my harness? Like I said above, I seem to have two plug wires for each glow plug. I am guessing I am running a separate harness for the glow plugs? One set is in use, the other is just dangling. Does this mean I just use the other plug on each glow plug and remove this second harness shown below?




Dazed and totally confused! I always wondered why I had two set of plugs for each glow plug.

 

[Mogman]

As CAMO said that is an old very outdated system, you will need a new engine harness and ether a smart start or CAMO box.
Take a picture of the "sqaure" connectors you are talking about at the glow plugs, the only thing I can think of is the civy setup with spade terminals.

 

[Mogman]

Actually it looks like the second harness was added later, you may have the harness you need for the later boxes.
What is the model/year of your truck?

 

[FlameRed]

As CAMO said that is an old very outdated system, you will need a new engine harness and ether a smart start or CAMO box.
Take a picture of the "sqaure" connectors you are talking about at the glow plugs, the only thing I can think of is the civy setup with spade terminals.

Here is a picture from underneath of the #1 cylinder. All the other cylinders seem to have a spare too.

Actually it looks like the second harness was added later, you may have the harness you need for the later boxes.
What is the model/year of your truck?

It is a 92. I was told the controller was replaced by the person I bought it from, but evidently he did not install a modern one.

 

[Mogman]

Well it looks like he just added the older glowplug harness, it looks like you can just remove that and install a later box, I am surprised the two types use the same main engine harness connector, I was thinking you said the extra connectors were square.

 

[Mogman]

I have not seen that two harness LAU box on the two 1992 trucks I worked on or any later trucks, I think the LAU boxes were gone by then, it is unfortunate but it looks like someone went through all the trouble of cutting a new hole just to install a crap box, at least your truck did not burn down because of it.

 

[TOBASH]

All they (LAU) do is add a second harness to the glow plugs.

You will need to reattach your primary glow plug harness. NOT HARD.

 

[FlameRed]

Thanks @Mogman !

So it if I got this correct, I should:

1. Disconnect the batteries
2. Replace the glow plugs (Ugh!)
3. Switch the glow plug connectors
4. Empty my bank account and replace with a NARTRON or KDS S3, or Camotek (no Santa this year)
5. Just connect the larger connector on the engine side and rip out the other harness (UGH)
6. Patch the extra hole
7. Reconnect the batteries

 

[Mogman]

I would test the glow plugs first, they may not be bad, you might also consider a Camotech manual box since you don't have any usable box, or yes an S3 box.
Stripping the old harness should not be all that much work.
I am still not positive the main harness is good to go, since you do have the extra glow plug connectors it looks like it but I am still surprised the old box would plug into the later style main engine harness, would be a stroke of good luck for sure!

 

[Milcommoguy]

Here's what I see / hear going on.... Looking close at the two photo, You have the later engine harness clamped up under the windshield. Noting the three 8 gauge wires on the rear connector.

Looks like someone had an old LAU box, an 8 wire glow harness, a big hole saw, some white ty-raps and time. Do what one has to do....I guess to "Keep them Rolling"

Pictures tell the story. Follow along with the other posts above or those to follow...... to get your truck straighten out. Keep that fire extinguisher handy.

Check with Santa, to see if you have been good.

I know some elf's at Camotek, CAMO

 

[FlameRed]

Deleted

 

[Retiredwarhorses]

You do not need to replace the engine harness….just remove the LAU harness and plug in the existing glow plug boots.
I stock S3 EESS boxes for less than $1k….shoot me a PM if interested.