How To Repair HMMWV EESS S3

Probably like most Humvee owners, the most likely part to fail (or to purchase with it already failed) is the PCB or Protective Control Box. And like most owners of multiple Humvees, I have a number of bad PCB's laying around. I thought it might be a good thread to discuss repair of PCB's. I have a couple that have the same issue so I will start with those. I can do circuit board repair, but not sure where to look for the problems. Hoping someone with an in depth knowledge of them will be able to chime in and help. Thanks in advance for your time. Really hoping that this is a start to an in depth PCB repair thread.

If anyone has any used PCB's (any variety) that they would like to sell, I would welcome a PM as well. I am in need of 2 of them right now.

My Two bad different PCB's (both Nartrons) that have exactly the same issue:

1. Nartron Yellow Label EESS 12469158-1:
2. Nartron Smart Start System 19207SOCN12480779:
Same Symptoms -> Lights glow plugs and wait light as normal. Wait light goes out and truck starts as it should. The Problem is that both continue to power the glow plugs until they are fried and the batteries never go to 'charge' (gauge stays in the yellow forever). After replacing the glow plugs with new, tried again, this time disconnecting the glow plug controller. Strangely, still never goes to charge while running (there must be something in the PCB that tells the alternator to begin charging?). So there are two (probably related) issues - the glow plug circuit stays on forever and the batteries never charge.

So these two Nartron PCB's are acting exactly the same. The truck starts/charges perfect when I install a known good Nartron or KDS yellow label PCB - so the truck itself and its wiring can be eliminated as the issue.

Thanks again for any advice and to develop this thread - would save a lot of PCB's from the scrap heap.

Dont have any overall pics but found this when I tore my KDS s3 box apart. There is a diode that fried and burned the board underneath. I also had one of the relays break and leave the glowplugs on which killed my batteries.

I just bought myself a m998 and waiting for the euc to clear. Luckily i employ a electrical engineer at my company. Since i am possibly weeks from being cleared, if you could send me a high res photo of the pcb, my EE can start to analyze.

I believe the reason there have been so many design iterations of pcbs is that the early designs failed repeatedly. Fixing the early boxes will just get you down the road a while until it fails again.

Just an FYI....a PCB is a PCB, an EESS is not a PCB. It crucial when diagnosing what's wrong when folks use the wrong terminology on these boxes...it is confusing, but it's a crucial piece of the pie.

also, if you look at the old schematic of a PCB...not an EESS, it shows 6 items in the box.
1. Wait to start lamp
2. Lamp check
3. Frequency lockout/load dump
4. Glow plug control
5. Reverse polarity load dump
6. Starter control

all of this tied to just about every POS and negative connection in the truck on the dash and anything that has voltage running through it. Meaning, just about anything can fry this box....hence, always disconnect the battery's.

Pictures of Nartron EESS and Narton S3

Thanks for the replies so for. Sorry for the wrong terminology - got in to a bad habit of generically calling these things PCB's, but you are right, that is not accurate.

I opened up the two boxes in question and attached below are the pictures. The first 4 are of the Nartron EESS and the second 4 are the Nartron S3 (I have others too, but will limit this to the two I spoke about in the original post).

If anyone has the detailed schematics for any of the models, please post and that will be a great reference for everyone. The more detailed schematics, the easier it will be to diagnose the likely components to check and replace. I could not find any schematics in any TM.

As you can see the EESS pictured shows evidence of moisture infiltration, but the S3 shows no signs of moisture, burning, etc. Based on the symptoms I originally posted, any thoughts on the likely culprit?

Where can I find an EESS box? I have bought a 1985 and was told it starts in warm weather but doesn't want to in cold weather. Any help is appreciated.

By the way I am new to this forum so be kind, lol.

Grant

BlueRoadster said:

Where can I find an EESS box? I have bought a 1985 and was told it starts in warm weather but doesn't want to in cold weather. Any help is appreciated.

By the way I am new to this forum so be kind, lol.

Grant

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Welcome. You may just need glow plugs.

Hi Grant - the control box is under the driver side dash - in front of your left knee when you are sitting in the drivers seat. A black box with a white, green, or yellow sticker on it and a round plug under the dash and another round plug in the engine compartment. First thing I would check is to see if you have good glow plugs by using a multimeter to test the resistance of the glow plugs - pull the connector off each of the glow plugs and touch one probe of the multimeter to the tip and the other probe to the collar of the glow plug (or any good solid ground on the engine). If any are bad, just replace them all. The resistance should be around 6 ohms if the glow plug is good if my memory is correct. If the glow plug is bad the resistance will be infinite (open circuit). Congratulations on your 85 - have fun.

The guy I bought it from said he replaced the glow plugs and had trouble shot it to the point he thought it was the EESS but I am reading here about having a matching TSU so, once I get it home I will start trouble shooting starting by knowing which EESS I have.

Thanks,
Grant

Z1classic, did you ever solve your problem with your bad EESS. I have a similar problem. My alternator does not charge either and my wait to start light stays on. Glow plugs are still ok.

We recently had a few days of rain and I just went out to start my 1991 M998 Humvee and now my wait to start light is blinking. Now it doesn't start. I have a Nartron Yellow label EESS box-19207, 12469158-1. I've been reading a lot about the EESS issues and how folks are going with the S3 control boxes from KDS. I figured I might as well take my out, open it up, and see what's happening. Here's some pics of the very surprising corrosion. I also got some pictures of condensation issues before it evaporated (not shown, but I can upload). I'm happy to see that the connections are marked well, so cleaning them up and reconnecting should be very easy. I don't see any evidence of burnt components. I'm taking a ton of pictures of this before I start cleaning all the connections. Right now, I think that the numerous corroded connections is the cause of my no start issue. More to follow.

jantkovi said:

We recently had a few days of rain and I just went out to start my 1991 M998 Humvee and now my wait to start light is blinking. Now it doesn't start. I have a Nartron Yellow label EESS box-19207, 12469158-1. I've been reading a lot about the EESS issues and how folks are going with the S3 control boxes from KDS. I figured I might as well take my out, open it up, and see what's happening. Here's some pics of the very surprising corrosion. I also got some pictures of condensation issues before it evaporated (not shown, but I can upload). I'm happy to see that the connections are marked well, so cleaning them up and reconnecting should be very easy. I don't see any evidence of burnt components. I'm taking a ton of pictures of this before I start cleaning all the connections. Right now, I think that the numerous corroded connections is the cause of my no start issue. More to follow.View attachment 650117View attachment 650118

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I that all the time...one issue is, don't forget to install the foam cushion seal on the top connector, that keeps the water out. I would seal up that area with silicon if you put in a new box as well as use the seal.

Nartron Yellow label EESS body connector pinout

I agree with sealing up in the top connector. Mine had the foam donut on top to prevent this, but it didn't work I guess. Once I'm done cleaning up the connections, I'm contemplating drilling some holes in the bottom of the case for moisture to escape. I've got the EESS outside with WD-40 on all the connections to loosen up the rust. I'll wipe it down clean when I'm done. I'm even thinking about putting an RTV on all the connections. I've been working on tracing down where things go. Here's a look at the internal under the dash "body connector" pinout for the Nartron yellow label EESS box 19207, 12469158-1. --

Just worked on the pinout for the "engine" side EESS box, Nartron yellow label, 19207, 12469158-1, Here's what I've got. FYI-I'm using the TM 9-2320-280-20-1 for the connector info. Pg. 2-135 can be referenced to get a better idea of the pins. I pasted it in for the engine connector, but it's hard to read.

jantkovi said:

We recently had a few days of rain and I just went out to start my 1991 M998 Humvee and now my wait to start light is blinking. Now it doesn't start. I have a Nartron Yellow label EESS box-19207, 12469158-1. I've been reading a lot about the EESS issues and how folks are going with the S3 control boxes from KDS. I figured I might as well take my out, open it up, and see what's happening. Here's some pics of the very surprising corrosion. I also got some pictures of condensation issues before it evaporated (not shown, but I can upload). I'm happy to see that the connections are marked well, so cleaning them up and reconnecting should be very easy. I don't see any evidence of burnt components. I'm taking a ton of pictures of this before I start cleaning all the connections. Right now, I think that the numerous corroded connections is the cause of my no start issue. More to follow.View attachment 650117View attachment 650118

Click to expand...

I don't understand why the Mfg. didn't dip these in a resin sealant like the civ market......probably a heat issue or a repairable turn-in item....I don't understand why, if life/mission depends on them there isn't a back up one on board.......Like a spare tire......

I agree with your concerns. I'm currently looking for a good coating to keep it from rusting and corroding again. I replaced all the rusted hardware at the connections and sprayed the board a few times with WD40. I also ordered a new relay and have the unit reinstalled without the cover on. I can measure the voltage on from the temperature controller and glow plugs. My alternator and heater work great now, but my glow plugs are shot. I should be getting a few ohms on them. I watched a few youtube videos and ran some tests from the 9-2320-280-20-1 tech manual. I've got a new set ordered. I'll upload more pics and some voltage measurements when the glow plugs hopefully work. I'm able to start the hmmwv up since the temp has still been around 70 degrees.

I just grabbed this from another site

http://www.hummerknowledgebase.com/electric/eess.html

jantkovi said:

I agree with your concerns. I'm currently looking for a good coating to keep it from rusting and corroding again. I replaced all the rusted hardware at the connections and sprayed the board a few times with WD40. I also ordered a new relay and have the unit reinstalled without the cover on. I can measure the voltage on from the temperature controller and glow plugs. My alternator and heater work great now, but my glow plugs are shot. I should be getting a few ohms on them. I watched a few youtube videos and ran some tests from the 9-2320-280-20-1 tech manual. I've got a new set ordered. I'll upload more pics and some voltage measurements when the glow plugs hopefully work. I'm able to start the hmmwv up since the temp has still been around 70 degrees.

Click to expand...

At work I have to service equipment with circuit boards that have been exposed to harsh environments.

I've had pretty decent success resurrecting some boards by cleaning them with Caig DeoxIT, degreasing with alcohol, and then coating them with Chemtronics Konform to protect them going forward.

You can find the DeoxIT on Amazon and Konform through either Grainger or Newark element 14.

I'm wondering if I should pull my KDS S3, open it up, and preemptively coat it....

Jakob1944, I've run across the link you shared. Thanks for your interest in the topic. With folks like myself buying HMMWV's from Govplanet, this will likely be a common problem. I've spent way too much time researching the EESS and troubleshooting. I'm hoping that my input helps others. If my eventual glow plug replacement works, I'll write up a couple page document on what I did.
Here's the one that I believe is the gold plated solution--http://psmag.radionerds.com/images/c/c8/PS_Magazine_Issue_710_January_2012.pdf. Check out page 12. These preventative maintenance monthly magazines are priceless. The S3's range from $300 on ebay to $590 on Erik's Military and Industrial Surplus, but I'm too cheap to buy one right now. I would very highly suggest that if anyone is having problems starting their HMMWV to clean up the major grounding points. I would pay special attention to the body ground (behind the gauges) and the engine ground (left rear of engine). Grounding kits actually connect the alternator ground, body ground, engine ground, S3/EESS mount points, and maybe even the starter. A poor body ground seems to contribute to weird gauge fluctuations-especially the fuel gauge and the gauge lights. In troubleshooting my EESS, I've replaced the Trombetta relay, cleaned up all connections (coated them with dielectric grease), inspected diodes and MOSFETS, and installed it without the cover. I've monitored the voltage from the temp sensor and it varies from 1.9 volts cold to about 0.4 at 180 degrees F. My alternator works fine (Volt gauge now shows in the green) and my heater blower motor is working too. I ran though the troubleshooting in the TM and my glow plugs are shot. I've ordered new ones. I'm thinking that my glow plug controller (in the EESS) should work with new glow plugs. I'm not getting any signs of glow plug cycling right now.
FYI-The terminology of the EESS or S3 Smart Start System or Protective Control Box (PCB from Prestolite) is all over the place. I can't imagine that anyone still has the old PCB (Reference in the TM 9-2320-280-20-1, pg. 2-227. I've got a Nartron EESS and a lot of folks have already moved up to the S3 (KDS seems like the best). If you want to start your HMMWV in cold weather, you have to have a glow plug controller that works. I would say that is the main reason for the PCB/EESS/S3. More to follow.