changed 13G'S to AC60's and now have voltage guage issue Need assistance

[M1009 NEWBEE 2013]

I changed out my 13G glow plugs, today, for the AC 60's and I also changed all of the connectors to the larger type and all went pretty easy without issue. Truck has started just fine all day, after the swap, no issues there either, yet. My issue is, that after the change, my voltage gage no longer appears to be doing the post start check (where the voltage gage drops to yellow and then goes to green 3 or 4 times, while running thru the checks). Now it goes to yellow, for 10 seconds +/-, then goes to green, without any further movement, after that 10 seconds or so. It just doesn't do the multi check any more. I read the sticky on GP theory of operation and cant seem to find what I did wrong. I checked all the connectors and all are indeed connected properly and I have continuity and the connectors are attached properly.
Can anyone advise what to check or maybe know what the problem is or help with this?? Or is this a problem? and now the new norm, after changing the glow plugs?
Any help would be much appreciated.
I'm driving it 1200 miles, round trip, this coming weekend, to pickup a new m101 trailer, from Kansas, and want to make sure I am road worthy. Thanks in advance for the info. FYI I have a new solenoid and did the DH relay and all has been/was good before the change. The gage did it thing this morning on the way to buy the connectors, then immediately after the swap this started.

Thanks All!! Dave

 

[doghead]

Do you see the same drop before the start up, as you had before the change?

Function should not have changed but the over all load could have(slightly).

I would not worry about it.

 

[paladin1176]

Are you still running the automatic GP relay? If so then the truck is cycling the glow plugs on and off until it reads that the engine is warm enough. You could try putting it on a manual setup or disconnecting it after you start it to see if you still get the same voltage drop when you start it.

 

[M1009 NEWBEE 2013]

Doghead, yes, all pre-start is normal and no changes. wait light cycles and all is the same prior to twisting the key. Just no cycling noted with the voltage drop after start up, just the one big long check, then goes to green and done.
I am a fan of keeping thing original and did not do the resistor bypass. Do you think I should? Also the removed glow plugs all looked good, only 1 checked bad.

Paladin 1176- I have the manual over-ride spliced in for emergency but have never used it. Dont think you can use it with the card in place can you?

 

[antennaclimber]

Doghead is correct, it sounds like your GP system is working as it was designed to. One bad GP will change the voltage to the remaining good glow plugs. The card was protecting the remaining GP's by cycling the power to them.

The after glow only happens when the card determine that it needs to perform the after glow function. This is a function of the GP card and is not a "GP Check".

There is no "automatic GP relay" in the system. The relay is controlled by the GP card.

Nor does the GP card keep the GP's on until the engine is warm. The time that it keeps the GP's on is based on engine temperature at the time of start and the voltage to the GP's. After the engine starts it keeps the GP relay closed based on voltage to the glow plugs and the resistance of the temperature sensor. The temperature of the engine is part of the equation but to say that it keeps the glow plugs on until the engine is warm is not entirely correct.

And yes, you can use the manual GP relay bypass with the card installed if you have your bypass wired correctly.

 

[M1009 NEWBEE 2013]

Ok, Doghead- quick update on this.
I decided to drive it to work this morning and all went well, pre-start was normal, wait light was normal (maybe a few seconds longer than used to, but normal) and it started just fine.
The cycling, after engine start, was one longer cycle in the yellow, then to green, then another cycle for 3 or 4 seconds and then to green. So it is cycling as before but only seems to go thru 2 cycles VS the 4 cycles I have always had with the 13G's.
I assume this (only going thru 2 cycles VS 4) has to do with the new AC60's (being all new, hotter, ect) and the card is sensing that it does not need any further cycling and all is good. I was stuck on the number of cycles, (its always been 4 cycles since owning the truck) but this is the first GP change so I have no real past history or baseline because this is the first time I've changed them.
So I guess my question is: Does the system have a set number of cycles it is supposed to run through or will it check as needed until it is satisfied it is sensing things properly? The reason for the info yesterday was that it was only going thru 1 long cycle and it never dawned on me that the engine was slightly warm after driving to the parts store. After an all night cool down, now its cycling, but only twice.
Also, do you think I should do the resistor bi-pass? or leave as original?

 

[M1009 NEWBEE 2013]

Antennaclimber- Thanks, I appreciate it. Our posts hit at the same time.

 

[Skinny]

I concur

I remember my GP system doing funky things before I swapped to a set of good plugs. If it starts cold and works...run it.

 

[M1009 NEWBEE 2013]

Doghead and Antennaclimber- Thanks for the info and the help with this. I feel better about my trip this weekend and appreciate you taking the time to square me away.

AC- I really only installed the manual push button for emergency only and prefer to keep things original (the systems, although old, work fine when not masked with suppose-ed upgrades) I know I have wired the push-button properly and just had a question; as you mentioned, I could use the push-button, even though the card is still in use. I assume turn key, push the button while the wait light is on, and when the wait light goes out, release button and start as usual? I have been reluctant to use it, as I was afraid I would damage the card if it was functioning properly. And with properly functioning card, how would I know which system was actually working? (would I have to remove the card?)

As mentioned, I prefer original, as designed systems and prefer to only install/change things that provide actual benefit (at least to me, based on my intended use) The DH relay and the manual push-button, for emergency only, are the items that make sense, at least to me. (other guys may have differing uses for their vehicles and may feel other items are a must for them, no issue there. However, I am interested in you're opinion (and anyone else that wants to chime in) on the resistor bi-pass. I totally understand the purpose and what could happen with GP failure. Is the bi-pass one of those must-do mods/changes??

 

[doghead]

I personally prefer to rewire the GP supply voltage to 12v.

There are several reasons. I've covered them all in previous threads.

 

[M1009 NEWBEE 2013]

DH-Yes you have, I have read many on this issue. I guess at the end of the day, one down-side would be lack of slave cable jump ability and if needed, you could swap the wire back pretty quick like, so that is a non-issue. I'm just on the fence here but probably not worth taking up more thread space talking about this one, as there are many previous threads on this issue. It just boils down to personal preference and when the cascade gremlin will strike.

 

[Skinny]

Playing devils advocate...how often do you get or need a NATO slave cable jump? Unless you own more than 1 MV (or had nearby friends) and actually posses the expensive cable, the setup is useless. Don't configure the truck around a scenario that for probably 90% of us will never happen.


Do the bypass, it is great protection to the GP circuit. Or just use 24v HMMWV GP's and bypass the card completely. The is the best of both worlds but you eliminate the automation of the OEM system.

 

[M1009 NEWBEE 2013]

Duly noted Skinny! I'm almost off the fence with this. Your right!

 

[doghead]

The nato slave cable will still work as long as the front battery is not dead and useless(open celled) or will not take any charge at all.

Just let it set for 5 min or so to charge the 2 batteries before starting.

 

[Skinny]

BTW, I dig your desert camo paint scheme. Looks good!

Doghead: assuming the front battery is dead but not malfunctioning with a shorted/dead cell issue, what if you had a single 12v jump pack on the front battery while jumping to a 24v source such as another MV or commercial truck? I would think even if the front battery wasn't taking a charge a good sized jump pack should be able to get the GP's hot and help crank the engine.

 

[doghead]

Yup

 

[Skinny]

Never tried it but figured it would work in a pinch.