NO Power to Glow-Plugs or FSD ? NO START

[Ed2000]

NO GLOW PLUG POWER

I have the following problem with my 1996 6.5TD suburban 2500:

When the key is turn to run, I get NO glow-plug light. I checked all fuses and they are okay. I checked the FDS and found no power on the

[tom.mcinerney]

If you're saying the starter doesn't crank engine and only one bank of glow plugs is active:
1.) Sounds like (A.) fusible links (B.) ignition switch (C.) PCM.
2.) There are fusible links on output of glo relay.
3.) There are lots other fusible links, may need wiring harness info for your model. Check output lead from alternator, that's fusible. Manipulate ignition switch and associated wiring to find loose connection....

[Ed2000]

No, the engine does crank over. Starter is okay, just NO glow plug light, and thus no voltage to relay, or PCM/FSD.

Thanks Ed

[diesel65]

The oil pressure switch has nothing to do with the glow plugs not working.
Turn the key to the run position, does the "service engine soon and service throttle soon" light come on?
If yes then you are getting power to the computer, if no then you need to check the ECM1 fuse in the underhood fuse box in the engine compartment.
If you have SES light but no glow light then check ENG1 fuse in the underhood fuse box, this fuse powers terminal A of the glow plug relay which should be hot in run or start position.
Check terminal C which is ground.

[Ed2000]

William,

thanks for the post. I have NO lights coming on when the ignition key is turn to the ON position, including the glow-plug light, and the service engine soon light. It seems all lights are missing. I have checked the fuses you mentioned, and they're okay. What I will do today is use my Volt meter, and check for power at the fuse location from where the voltage is supposed to come from the ignition switch. After much reading on the Diesel Page last night, it seems that others have had a similar problem having do with the ignition switch harness wiring. Hell, I have never taken the steering column apart to check that, and not sure where to start. The other thing I have heard much like you mentioned is the bad ground. I will check that today.

A clue to anyone if this means anything. Before the engine quit all together, it ran with the service engine soon light for about an hour before my wife even told me about it. She was afraid not to make it home, so she continued on. The trucked stalled on her once, she placed it in neutral and restarted the engine. Now the service engine light was on again. She then made it home and told me what happened. She mentioned the glow-plug light was not coming that morning, when she had to turn the ignition key several times before it would finally come on. Well, I went to check the truck, and the first time it started right up, but the service engine light was on. I shut the truck off, and tried again and this time the glow-plug light would not turn on, and neither any of the other dash lights. From this point on, I have not been able to gets lights on the dash back on, or re-start the truck. Oil level is fine BTW. Not sure what the service engine light is about, other than the PCM sending a failure code. I did try a backup FSD, and no lights. I then tried tracing all voltages, and no voltage anywhere around the FSD, or Relay, etc. Its like no voltage is getting from the starting point of the ignition switch.

Well, have I confused everyone yet? Please excuse any typos, etc., I have not had my first cup of coffee this morning. Did not sleep well as a result of this problem. I really do not want to give up on this 6.5, but the wife has had it. There is a guy in Georgia who will convert this 6.5 electronic fuel systems back to a manual system, but must add a new computer for it work with the transmission, cost $1,800.00. I am wondering if when the engine is due for rebuilding, maybe I should get rid of the electronic stuff.

Thanks to all for any comments.

Ed

[Ed2000]

Okay, I made some progress, but here is the million-dollar question:

If I keep turning the key back and forth many times, it will finally light the entire dash lights, and automatically lock down the automatic door locks. At this point I can start the vehicle with no problem. While the vehicle is running, I can play with the area of the steering column, and mess with the ignition area of the key, but the truck will continue to run, NO stalls. If I shut the truck off and try and re-start, NO light, or glows plug light. I must once again go back and forth with the key multiple times till all comes back. The question is, is it a bad ignition switch, or a bad ground somewhere on the truck? Why is it that once the truck starts, it will continue to run with stalling? If there is an intermittent electrical failure, it should stall the vehicle at times, right?

Question, if one battery is bad, but both indicate 12 + volts while connected together, can there be some type of bad short to ground, etc? How do I go about finding the bad ground if that is the problem? I am not sure how you find an intermittent problem like this.

Ed

[ucdavis]

Ed,
Sounds like you have isolated trouble to one of two spots or combo of the 2:
Ignition "switch", and grounds.
The switch that goes bad is (usually) below the key assembly in the steering column. Many get prompt temporary relief when this is the culprit by manipulating the tilt wheel a few times w/vigor.
The ground (& this sounds like a likely issue to me) is under the dash. Yours is different than mine, so I don't know exactly what the dash main ground looks like, but it should go to frame metal from a lug on the back of molded dash.
re: bad batt- you should disconnect both batteries to test individually; one bad batt will kill a good one. Test w/hydrometer for full charge. Or, after they have been disconnected 30 minutes or so or you have run a load off the disconnected batt (small 12V light or fan will do, direct off the terminals to skim off any surface charge, you can check volts for 12.6V+ Much less & that batt isn't charged fully & may not be taking a charge (hydrometer is most certain way & fool proof).

[Ed2000]

So do you think a bad battery can cause this strange effect with the lights not working all the time?...humm As for the ignition switch, it looks like a bear to change out, plus it will cost $118.00. I am not sure if I should change that out first. The local Chevrolet dealer want $60.00 to check it out and tell me what is wrong.

Have you or anyone else changed out the ignition switch?

[turbovair]

Ed 2000,
CHANGE THE IGNITION SWICH ASSY. Its fairly easy to do. Buy a new one. Its about $180 but worth it. I had problems virtually identical to yours. While the engine was running, I wiggled the ignition switch and it died. Upon restart I had no dash lights until I wiggleg the switch. Trust me. CHANGE THE IGNITION SWITCH ASSY.

[turbovair]

Ed,
Change the switch harness assy. It mounts UNDER the lock cylinder in the column and has a wiring harness extension attached which connects near the base of the steering column. I bought mine brand new from a dealer.Took about 2 hours to install. Not too difficult. Had to make a special tool to remove the two male torx screws holding the switch to the column.Also, I made a small cut in the lower plastic shroud to enable me to get it off without removing the lock cylinder. My truck began random stalling just as yours does. When I noticed wiggling the key made a difference, I replaced the switch per info I recieved here. Good Luck.

[tom.mcinerney]

How many miles on this rig?
After renewing ig switch have a mechanic check the charging system, and do a load test on both batteries.
The alternator may be tired, need rebuilding. The battery cable grounds and other harness grounds on engine may need cleaning/retorqueing.
A healthy alternator is necessary to preserve the electronics.....

[Ed2000]

I think I fixed the problem with the ignition switch, "No start problem". What I discovered was that the second wire (red) leading to the ignition switch on the steering column, was NOT making good contact. Every time I would press firmly with a screw driver on the contact, the dash board light would light along with the glow-plug light, and the truck would start. What I did next after much consideration for the cost of a new switch $118.00, plus the installation, I tried sometime that some will laugh at me. I used a small 1/4 inch wood screw and tapped it into the faulty contact, which held it firmly. The truck has now started every time. Lets hope this simple solution works...knock on wood!!!!

[tom.mcinerney]

Good job! But be vigilant regarding alternator , batteries, and all engine grounds. The electrical system is slightly underdesigned; bad connections heat up and become worse connections....