M998 No POWER to ANYTHING 6 volts only !

Had as friend swap out the ECM to a newer version of the S3 after his truck was eating glow plugs. Ended up getting it back to my shop, since the install of the S3 / and multiple S3s on my end I am coming up with a weird one.

Friend swapped out the Glowplugs/ s3 as it ate them in 200 miles! ( swelling )

Since the install of new GPs and S3 we have a no start situation. No Clicking / No dash lights / ( still have operating lights )

I have already checked grounds / Run through the TM.

S3 is putting out 24 volts but when I trace it to the Wait light at connection 571 Still 24 volts / once I hook up the wait light to 27L it goes down to 6 volts / also 6 volts at the main fusible end links behind dash.

I already tested the starter, and it fires off when I send signal. I can add a lead from alternator main feed to 27L and I get gauges to operate, but no ECM chatter or wait lights.

TM is saying replace ECM again, but I just don't see how thats possible. (Yes batteries were unplugged prior to Swap out )

Could I have a potential problem with a body harness? I checked most all connections and they are showing continuity?

Once the power gets to the Wait light / I know it shares the same circuit as the brake light on the dash then power is split out from there to multiple locations.

I ordered new fusible end links today... just because the original ones were in not so fair of shape.

Any thoughts would be nice, been on it for 14 hours so far, and someone throwing in any feedback will keep me sane for a few more hours.

Since you have two trucks between the two of you (I assume), you could always swap the potentially bad box into the other truck and see if it exhibits the same problem. That would tell you if the box was bad. Those things are stupid expensive, so I understand the reluctance to throw another part at it. Alternately, if you buy a new box and it turns out the problem was something different, you'd have a spare.

riderdan said:

Since you have two trucks between the two of you (I assume), you could always swap the potentially bad box into the other truck and see if it exhibits the same problem. That would tell you if the box was bad. Those things are stupid expensive, so I understand the reluctance to throw another part at it. Alternately, if you buy a new box and it turns out the problem was something different, you'd have a spare.

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Was actually going to do that tomorrow! I have a dozen sitting at my property

There are only 2 ea. circuit breakers under dash....no fuseable links.
CB's are either good or bad.
29 D, and 27 D.....check them un plugged with ohm meter.
S3 box should always be changed with sensor............KDS S3 uses CR 2696A,.......Nartron S3 uses 12480779-2.
If Batteries are fully charged, Alt. operates at 27.5 vdc, correct Box / sensor combo, and good GP's and fuel...should start right up.
You can take box out, open it up....If its bad, you will normally see a burnt ground, or component or moisture damage.

Oh good
Now you have me studying all kinds of stuff I am never going to have
Look in here.................

https://www.steelsoldiers.com/showthread.php?151646-How-To-Repair-HMMWV-EESS-S3

and this is referred to in the above post

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

The Cannon connector the points upward from the start box in the engine compartment is known to get corroded between the wire and the terminal resulting in all kinds of bizarre things like you described. It will ohm out good, but not pass an electrical load.

86humv said:

There are only 2 ea. circuit breakers under dash....no fuseable links.
CB's are either good or bad.
29 D, and 27 D.....check them un plugged with ohm meter.
S3 box should always be changed with sensor............KDS S3 uses CR 2696A,.......Nartron S3 uses 12480779-2.
If Batteries are fully charged, Alt. operates at 27.5 vdc, correct Box / sensor combo, and good GP's and fuel...should start right up.
You can take box out, open it up....If its bad, you will normally see a burnt ground, or component or moisture damage.

Click to expand...

* Circuit breakers * that is what I was referring to.

Thanks

Perkman87 said:

* Circuit breakers * that is what I was referring to.

Thanks

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Also it did check out on the continuity test, I just don't like the overall condition of the boots.

NDT said:

The Cannon connector the points upward from the start box in the engine compartment is known to get corroded between the wire and the terminal resulting in all kinds of bizarre things like you described. It will ohm out good, but not pass an electrical load.

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brand new Engine harness. But I will check.

riderdan said:

Since you have two trucks between the two of you (I assume), you could always swap the potentially bad box into the other truck and see if it exhibits the same problem. That would tell you if the box was bad. Those things are stupid expensive, so I understand the reluctance to throw another part at it. Alternately, if you buy a new box and it turns out the problem was something different, you'd have a spare.

Click to expand...

Swapped ECM. ECM is good....

Check the wiring harness forward of the steering column.

When I got my truck several years ago, my PCB was toast - hard starting, eating GPs, etc - replaced it with an S3 box, but I also had a loose steering column due to some broken aluminum tabs made out of unobtanium, so I bought a complete, new style column to replace it with.

While it was out, I could see the main bundle of the wiring harness had slipped DOWN off the half-clamp (kind of a very thick, largish Adel clamp which is supposed to hold the bundle to the fwd footwell) and the wiring insulation had worn through exposing several RED wires, about 8-10 gauge presumably positive, to the column. I teased these out, insulated them with vinyl and silicone, rewrapped what I could and used YUGE zip ties to hold everything up out of the way.

Of course, YMMV, but you might want to look at that while you're under the dash poking at the circuit breakers.

NB

NormB said:

Check the wiring harness forward of the steering column.

When I got my truck several years ago, my PCB was toast - hard starting, eating GPs, etc - replaced it with an S3 box, but I also had a loose steering column due to some broken aluminum tabs made out of unobtanium, so I bought a complete, new style column to replace it with.

While it was out, I could see the main bundle of the wiring harness had slipped DOWN off the half-clamp (kind of a very thick, largish Adel clamp which is supposed to hold the bundle to the fwd footwell) and the wiring insulation had worn through exposing several RED wires, about 8-10 gauge presumably positive, to the column. I teased these out, insulated them with vinyl and silicone, rewrapped what I could and used YUGE zip ties to hold everything up out of the way.

Of course, YMMV, but you might want to look at that while you're under the dash poking at the circuit breakers.

NB

Click to expand...

I will check today.

Perkman87 said:

I will check today.

Click to expand...

Nope that portion of harness is fine.