Wait light Quick blink only

[Stevev]

Good morning
im new to this sight but have found it to be a great help
thanks for all the info and posts
I have a 1989 m988 my voltage reg went and was spiking 37v at times
I fount this out when my wait light just did a quick blink and my truck had a hard time starting
I replaced the voltage regulator and all is good 27.7v steady now
I’ve done all the basics on troubleshooting with my glow plug issue
new plugs,ran a new ground harness,checked connections ect
my volt meter does not move or bounce when I put on the run position
all the gauges and other components seem to be working the truck
I have a KDS green controller with a white label that says smart start system
and the sensor on the motor has a yellow band
any suggestions before I bite the bullet and order a new controller
Is it recommended to add a external glow plug button
if so any how to info would be great
love this Humvee just want it to start this winter
thank you for any help or suggestions

 

[Retiredwarhorses]

Unplug the TSU connector and plug it back in....S3 EESS isn’t seeing the TSU

 

[Stevev]

Thanks bud
I will try that when I get home
if it still does the quick blink
should I order a new tsu could it be bad
one other thing I found is when the truck is warm the quick blink goes away like it is sensing the engine temp

 

[Stevev]

Just unplugged my tsu and replugged it in
same problem
I check the ohms at the glow plugs got 2.9-3.1
tested to see if I have power at the plug boot
and nothing when I turn the key on
I did turn the key on with the tsu unplugged and the wait did the same quick flash
also when I turn the key off I do here a clunk from the controller box like it’s doing something
any chance the tsu could be bad even tho it does sense when the motor is 120 degrees and the wait light doesn’t flash when I start it?
thanks for your help

 

[Retiredwarhorses]

TSU just determines if the motor is 120 and above or 120 and below...if below? It starts the glow plug cycle, if above, it won’t.
sounds like a bad box....

 

[DREDnot]

For what its worth, At the 8:19 mark, they show how to check all the pins on the "Glow Plug Controller".
I'm not sure if this is an earlier style unit than the TSU and it may be altogether different.

https://www.youtube.com/watch?v=hBA0QRg0a8g

 

[Stevev]

Thank you very much for the help
I found a post that shows how to run new glow plug wires and bypass the controller with an external bottom
That’s probably my best bet to fix the problem ����
kills me to by a new box for $700+ and possibly have it happen again

 

[papakb]

The early Protective Control Box (PCB) used a Glow Plug Controller (GPC) on the water crossover manifold to determine engine temperature and make the decision to either heat the glow plugs or not. The Newer ESSS boxes use a Temperature Control Unit (TCU) to do the same thing but the 2 pieces, while similar in appearance are not interchangeable. You need to make sure the control box and the sensor you have are a match. Do some searching here on the SS sire and there are several posts about what goes with what.

 

[Stevev]

Thank you for the help
I ordered a new tsu with the yellow band that matches the one in my truck
I’m so hoping that does the trick
everything was working great until my voltage reg went and juice my system
with 37 volts spikes ever so often
mid this doesn’t solve it I’m going to do the new glow plug wire harness to a push button bypass that I read about
seems like an easy solution
this site is awesome with all the help
And knowledge
thanks again

 

[Stevev]

Thanks for all the help
just replace the smart start box
all good now!!!