Glow plugs work first start only

[Atchuuu]

Glow plugs work every time after I disconnect the battery and hook them back up. I base this on the fact that the wait light blinks, voltage meter fluctuates and the fact that the truck starts right up.

however, once shut down, even if it is cold outside and the truck has not been started for a couple days, the only way to get the wait light and voltage fluctuations is to disconnect batteries.

Any thoughts? GP are new

 

[Mogman]

A couple things, the voltage should not fluctuate until the main timer has timed out, 8 seconds or so, then it goes into "after glow" where the EESS turns on and off the glow plugs to keep them warm for about a minuet or so, then they turn off.
If the wait light is just "blinking" and the EESS goes into afterglow it will start, especially if you wait 15 seconds or so as they will warm up but more slowly.

You need to go through the troubleshooting guide for the glow plugs, hopefully someone will post as I do not have them handy.

This is also why I have a light on one of the glow plugs to actually see what the glow plugs are doing, I do have one EESS box (I rotate them every time I service the truck) that at times will only go into afterglow but because I can see that I just wait 15 seconds or so and it starts right up.

Battery switches makes it easier too, as I do not have to even pull the seat to service my electrical system.

 

[MarkM]

Take baby steps. Check each plug (still in the engine) with a meter to see if they are still viable. If the plugs are good it is more than likely the box is having issues and is very common. Many of us keep a good spare box around just for these issues.

I put in a new set of plugs (PITA) only to find out they all burnt-out in two min because a relay in the box was stuck and kept power going to the plugs.

Remember the box and the glow plug temp unit on the block are a matched set as there have been many revisions to the glow plug system because of all the failures.

Mark

 

[Atchuuu]

If I use a battery kill switch it solves the problem of the wait light not flashing after the first start. Essentially it’s like disconnecting batteries each time. Are they any reasons that this is not an acceptable fix rather than a new box?

 

[Coug]

If I use a battery kill switch it solves the problem of the wait light not flashing after the first start. Essentially it’s like disconnecting batteries each time. Are they any reasons that this is not an acceptable fix rather than a new box?

I don't see why not. I've had a battery disconnect switch in my truck for 3 years now no issues
It's not so much a "fix" as a workaround. Who knows how long it will continue to work in this manor, and it could decide to stop working entirely in a matter of weeks, or might work for many years

 

[Retiredwarhorses]

Flashing wait light is a TSU…

 

[Mjoeyroo]

If I use a battery kill switch it solves the problem of the wait light not flashing after the first start. Essentially it’s like disconnecting batteries each time. Are they any reasons that this is not an acceptable fix rather than a new box?

What disconnect switch are you using?

 

[Atchuuu]

What disconnect switch are you using?

I’m using a boat type switch with red, removable, handle. It wired to the negative side. It has worked perfectly and the wait light does too if I use the kill switch in between starts. If not, the box doesn’t heat up the plugs as shown by the volt gauge.

something similar to photo shown. I think mone
Is rated higher amps but don’t have access to receipts right now.

 

[Atchuuu]

What disconnect switch are you using?

This one

 

[Mogman]

If I use a battery kill switch it solves the problem of the wait light not flashing after the first start. Essentially it’s like disconnecting batteries each time. Are they any reasons that this is not an acceptable fix rather than a new box?

That does not make sense, you cannot disconnect the batteries while running so how does that fix a flashing wait light, as RWH said it is likely a bad or miss matched TSU

 

[Mogman]

This one

That switch is way too light for the HMMWV as it is only rated at 100A, just because someone is selling for the HMMWV means nothing in this world, you need one like this one, it is rated at 1500A .
https://www.ebay.com/itm/134800750921?
If you have a dual voltage system you actually need two switched, that light duty one would be OK for the 12V tap.

 

[Atchuuu]

That does not make sense, you cannot disconnect the batteries while running so how does that fix a flashing wait light, as RWH said it is likely a bad or miss matched TSU

I discovered that the wait light was functioning just fine on the first start only. In other words, after it started once, the wait light did not flash, even if engine cooled down or sat fora couple days.

with the kill switch, I turn it to on to start the truck. TSU works fine. When I get to destination, I turn kill switch to off position. Repeat process when I get back to vehicle. Wait light works every time.

the how or why this works doesn’t concern me. It does and saved me from buying a new control box.

 

[Atchuuu]

That switch is way too light for the HMMWV as it is only rated at 100A, just because someone is selling for the HMMWV means nothing in this world, you need one like this one, it is rated at 1500A .
https://www.ebay.com/itm/134800750921?
If you have a dual voltage system you actually need two switched, that light duty one would be OK for the 12V tap.

Thanks for the link. Looks heavy duty and it’s reasonably priced. Should mine fail I would consider this for sure.

I do have dual voltage but am using a 24-12 converter rather than using tap on alternator.

thanks for the information