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Intake Ground Stud-bolt

Any update Louis?????????
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Well now I'll run and it seems that when I do stall, it's only while at "Idle".......So I'll, pop the hood, jump out with my 15mm ratchet, loosen the nut on the "intake" stud, where all 3 grounds are now, stacked up with washers in between, swivel the eyelets (without removing any), tighten the nut back up and she'll fire. So far, like I said this is only at "Idle".

Mind you, Still haven't fixed the broken ground strap from the tranny dip stud and when I do........I'm gonna take out the stud, shine it up to a mirror like finish and return that ground to it's original location......I'm not liking the 3 stacked grounds on that 1 intake stud. Also that stud and it's surrounding area (don't know if that one comes out) need/will be de-greased and wire brushed (AGAIN) and I will add another Braided strap from the dip stud to the intake stud. I found the exact matching strap in AZ help section, so I will be changing the 2 OEM frame to firewall - firewall to dip stud and adding - dip stud to intake stud.

Also, I now need to extend the ground wires from all the snipping and changing eyelets, I'll need to find an expert in soldering, as I have never even held a soldering iron.......and I hear their is a skill factor involved. ( I would cut and crimp the extensions in, but I feel the connectors are inferior to a good solder connection)

If you haven't replaced the ignition switch yet, I'd go ahead and do that. It was the last thing I did to the 96 Suburban to put the WTS ghost at bay.
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If this don't work, that'll be my next move......BUT, I know it's these friggin ground wires because, when I stall, the PCM looses it's power/memory......There is a SES light on (From a boost code) and every time the Ghost appears, the SES light is out till next key cycle.

Also, "Simon says"(LOL):)(AKA Bison) it could be power that I'm loosing instead of ground and pointed me in the direction of the under hood fuse block/box, which I've heard have a track record of getting skechy:skep:, so I could be on the opposite side of this issue, chasing bad grounds when it could be a hot/positive issue?......And then again, ignition???:WTF:
 
Have a hard look at the ground wires again,see if you can find a weak spot in them by flexing here and there.
Its not the first time a wire core fatiques and breaks in side the jacket,sometimes with only a single strand intact.
 
If you haven't yet, it's a good idea to add a ground to the blower motor. I run a 10 or 12 wire ground to the dash bolt right next to the blower using a 3 way spade connector.
 
buddy said:
You could try splicing into the wires right at the PCM and run a parallel grounding to a good chassis ground.
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Anyone have diagram/schematic of the plug/wire/pin locations for those 4 particular PCM grounds.....That sounds like a good idea and would eliminate any bad wiring in the harness.....Idea being, the harness from the cab side of the firewall, straight to ground.....correct?

That would eliminate any ground issue from the firewall engine side.....Or at least a fail safe back up for the PCM.


If you haven't yet, it's a good idea to add a ground to the blower motor. I run a 10 or 12 wire ground to the dash bolt right next to the blower using a 3 way spade connector.
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It's amazing how hot that connector/plug gets, as to actually melt the plastic housing......Tackled that one already the last time I changed the blower motor.
 
your PCM grounds go to pins D6 and D7. Each of the PCM harnesses will have labeled rows, A and B on one, C and D on another. then each one is likely labeled with its number location too.
 
Louis, Which specific diagrams would be of help for you? I have access to the diagrams for my 99 if that is any help.

I know the farthest back stud was the problem for my passlock issue on the 99. I think it's where the tranny dipstick goes to (mines a manual so i'm 100% sure on that). The large black wire from the loom is pretty much the main ground for the entire computer system in the truck. There are a few inline connectors with it as well.
 
OK....WTS is back with a vengence, AGAIN!

I even doubled the ground on the intake stud with a gnd cable straight to the Neg batt terminal......Seems those grounds (the 3 coming from the harness) are not the cause of the issue.....Now I'm thinking Ignition switch, BUT, still sometimes have a "flickering" ses light.....Not like a code flash, but "flickering" like there is very little power too it (or a bad gnd).....Maybe I'm loosing power? where would I look for that?

What, where, to look next.....need help!
 
Sounds to me like you have a short somewhere in the IP cluster or it's wiring. The WTS light and SES lights are both constant powered when the truck is on, and grounded via the PCM when they need to be illuminated. When the WTS light does the battery voltage drop down? If it doesn't then the relay isn't kicking on telling me it's something else in the cluster. I would start by checking the connector on the cluster itself, if the contacts aren't clean and they aren't making a good connection the cluster won't work right.

I also traced the grounds, the PCM, IP cluster and glows are G104 and G105, both of which are those studs on the motor....
PCM.gif

IPIndicators.gif

DieselIndicators.gif

GlowPlugs.gif
 
David, IP fuse Cluster/block.....Thats not the underhood fuse block....Correct?.....IP fuse/block/cluster is the one under the dash? or am I missing something here?

And when the WTS doesn't lite, the voltage does NOT drop, also some times the ses light will be ON strong/bright other times it'll be "flickering" like bad power/gnd.

Just not sure what your referring too when you say "IP Cluster/block"
 
IP fuse block is the one on the end of the dash.

The WTS light and SES light are both on their own circuit and are controlled by the PCM. The glows are also controlled by the PCM. I had forgot you were getting a no start condition. Have you checked the plugs for the PCM?! I'm starting to suspect the PCM may be having the problems since it controls both.
 
88gmctruck said:
IP fuse block is the one on the end of the dash.

The WTS light and SES light are both on their own circuit and are controlled by the PCM. The glows are also controlled by the PCM. I had forgot you were getting a no start condition. Have you checked the plugs for the PCM?! I'm starting to suspect the PCM may be having the problems since it controls both.
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IP block end of dash=I'm retarded.....sorry, forgot about the most obvious fuse block on the truck.

And the WTS and STS is what goes out when there is a no start condition......SES (MIL) is either on strong/bright or "flickering," like a bad power or gnd.
jrsavoie said:
Has the ignition switch ever been changed?
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NO, thats next just to rule it out.....But the ign switch would energize everything, BUT the WTS/fuel/STS if bad?

http://www.thetruckstop.us/forum/showthread.php?29076-3500-and-3500HD-Ign-Switch
 
Sorry Louis, I've been having some vision problems and I was missing STS and SES.

So Wait To Start (WTS) and Service Throttle Soon (STS) both go off when you have a no-start issue, and the Service Engine Soon (SES) is bright or flickering. Now when you say a no start condition, is it that the starter isn't turning at all or the truck cranks and will not fire.

I'm assuming that it isn't cranking, and if so, here is what I would do to diagnose:

Fuses: Obvious, but sometimes overlooked. Physically make sure every fuse is intact. You can also verify that any fuse labeled "IGN" receives power when in run.
Underhood fuses: IGN A & IGN C - always hot (power the ignition and the starter relay)
Dash Fuses: IGN 1 & IGN 0 - Hot in start and run. Crank - Hot in start

StartingFuses.gif



Ignition: The easiest way to test that it is making a connection in the "start" position is to roll the key on and verify the "crank" fuse is getting 12v, as it controls the starter relay.

Starting.gif



Starter relay: Relays can wear out. I'm not 100% sure, but IIRC your 96 will also have this relay in the underhood fuse center. It is powered by the "IGN A" fuse in my truck, and the ignition signal is the "crank" fuse.

IgnitionLHbattery.gif



IP Cluster: All the warning lights in the dash are controlled by the same power source, and grounded by either different sensors or the PCM, so if you have ANY lights at all this tells me the lights are getting power and the respective control is either lighting or not lighting them. As a precautionary to shorts, try starting the truck without the cluster in to rule it out of the equation. The truck really doesn't care if the cluster is there or not, it would start with or without it, so lets assume it has a proper connection.

PCM: First off, have you checked the connections at the PCM? All of the lights in question (WTS, STS and SES) are directly controlled by the PCM. Since the PCM controls these lights, it would be my first suspect.
 
IIRC it wil crank (turn over) but not run until the lights come back on. My vote is for the pcm connections or the pcm itself.
 
If that is the case, then I'd be suspecting the PCM myself as well, since those lights are directly controlled by it.
 
SES is always on when keyed on, sometimes it's "bright" and sometimes it's "flickering".......but it will always come on with key on. (which is leading me to think either bad power or gnd)

The STS light is the tell all, when I key on and if I don't get a "STS", I will not get a WTS and the truck won't start.

The truck "ALWAYS" cranks......NO problem with starter
 
There has got to be something wrong with either the PCM or the connections to it. You've checked the ground for it already, what about it's power source? In the underhood fuse block, check "injector 1, 2"(hot in run and start) and "ECM B" (hot at all times). They are the power to the PCM.

Have you tried disabling the fuel shutoff solenoid?! PCM is in control of that portion of fuel flow prior to the actual IP fuel solenoid, which the PMD controls.

I looked into the throttle control, there are no outside variables with it, it's entirely connected to the PCM. I'm going to check a hunch after work and unplug my throttle and see if my STS light will not come on.

This is the problem with the electronic injection on these... If a sensor or connection is bad etc it will tell the PCM which in turns tells the PCM to cut fuel. So for whatever reason your PCM isn't allowing fuel otherwise your truck would fire right up. It doesn't sound like it, but your PMD might be going bad so lets not entirely rule that out either. Same thing happened when my passlock module went out, truck always cranked, just never fired. I didn't have ghost lights, but the principle is similar.
 
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