Was having problems with the thermal switch on the passenger side of engine by firewall, bypassed that and now plugs cycle everytime. Not sure if I should also replace controller, what do you think? Now next, because I have had these difficulties with that switch, I have been turning the starter a whole lot. Then when it turned, it turned pretty slowly, sometimes it starts, sometimes it doesn't. Now, when I turn the key, I get nothing. No light, no nothing. In fact if I turn the headlights on and try to start, they don't even go dim. Man this is a pain in the ^&%. Can any assist with this and/or supply me with some feeback? The starter was new about 14 months ago, the batteries (Megatrons), were new in Dec. of '04. Thanks much.

Oh, and this is on a '85 K5 Blazer with less than 100,000 miles on this engine.

And to add insult to injury. Because it was having a hard time starting, cranking real slow, the starter that is, I was cirious if it was the batteries reading low even though with a multi-meter it said almost 13 volts. Well I put a charger on it, one of those with 3 options, with one being fast start and turned the engine (it did turn a little faster) and it started. Shut it off, tried it again then nothing. Tried it again, then something, maybe the starter made a loud sharp noise, and it started again. Turned it off and then tried to start again, but got no lights or anything. Can't even roll up the power windows. Kept trying and after a few times, it managed to start one more time. I turned it off. Now when I turn the key on, I got absolutely nothing except I can turn the lights on. Although I did shift it from park to neutral and the dash lights flashed on really quick only to go off again and not to come back on. What is going on here?! :help:


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Di I have a fried starter and ignition? Damn...this really sux!

I had same kinds of problems last winter... Turned ignition switch on, pushed the manual gp switch and when I tried to start... Nothing :confused:

Ignition off, and tried again, same thing, no power. Then I tried lights, they were okay. I was thinking that starter is fried. Pop the hood and checked the battery cables. And what do you know, ground was loose. Tightened it, and never had same problem since.

All other accessories worked fine, they don't need as much power as the starter does, so the loose connection suplied enough juice to them work. But starter takes something like 550 amps, and that loose clamp just could'nt handle that much.

Okay, I did wiggle the wires around a little bit and was about to get the glow plug lights to come back on as well as power for the windows and such. But only last for a few. Then when I turn the key, it goes away and I have to woggle the wires again and then maybe it will do the same. The wires on the batteries and all seem tight. So I am wondering if a cable is bad or something or got friend. Plus the starter really doesn't do anything, so I think it is fried. So what do you all think?

Also, as I had mentioned earlier about just closing the circuit by pinning those 2 wires together that go to the thermal switch, what do you guys think of that? Was a suggestion from someone who seemed to know what he was talking about.

Thanks for any more input you guys can provide. Must be a little slow here on the weekends.

Shorting those two terminals will run your fast idle and cold advance solenoids all the time, which is not a good idea. Replacing the switch itself only takes about 2 minutes if you have a wrench or socket to fit it (3/4" IIRC).

Do you have top post or side post battery cables? Your circuit tester shows 13 volts at the batteries, do you know what rating they are? CA and CCA (cranking amps and cold cranking amps) You can't get batteries too powerful, but a lot of auto places will sell you 650a batteries becuase thats what their computer shows and they have no knowledge about diesels. I run twin 1050a on mine, starts like a champ.

You either have corroded terminals that you might be able to clean and make work again, but it is possible that the corrosion has spread into one or more of the heavy battery wires and they need to be replaced.

If cleaning and tightening the terminals and grounds doesn't work, then it sounds like your going to have to pull the starter off to have it load tested and probably replaced.

I bypassed the controller in the left head by installing a manual switch for my glow plugs. I kept the thermal switch in the right head so the glow plugs will not go on when the engine is warm.

Your starting problems might be from a loose battery terminal connection at your starter solenoid (on the starter).

Shorting those two terminals will run your fast idle and cold advance solenoids all the time, which is not a good idea. Replacing the switch itself only takes about 2 minutes if you have a wrench or socket to fit it (3/4" IIRC).



No,
The fast idle and cold advance is on a different sensor, that sensor is screwed into the head on the passenger side near the exhaust manifold.

Can anyone add anything to my last post?

Okay, I did wiggle the wires around a little bit and was about to get the glow plug lights to come back on as well as power for the windows and such. But only last for a few. Then when I turn the key, it goes away and I have to woggle the wires again and then maybe it will do the same. The wires on the batteries and all seem tight. So I am wondering if a cable is bad or something or got friend. Plus the starter really doesn't do anything, so I think it is fried. So what do you all think?
I think you have some electrical problems to sort out. We can help point you in the right direction, but we can't fix it for you.

A very, very high percentage of starting problems with a lt. duty diesel, especially a 6.2 involve battery cables and connections. They are a real problem because of design. Clean and tight is an absolute must. Be extra sure and careful about the double cable and spacer on the positive post of the rt side battery. Lots and lots of problems. Spacer gets corroded, dented by "teeth" on cables, etc.

Aftermarket batteries add to the problem as they almost always "leak" acid onto the terminals. This speeds up the occurance of the corrosion/loose connection stuff. The ill-designed, "use the bare minimum size" cable syndrome adds to this problem.

Once again, CLEAN, TIGHT cable connections and a GOOD starter are the keys to proper cranking speed and a quick starting 6.2!

DITTO! Get those battery connections spotlessly clean, including removing the lead spacers and cleaning behind them. Baking soda and water paste works well for cleaning the terminals. Also check conections on starter and grounds on engine block and make sure they have good clean metal under them.:grd:

I had the same poblem but i had fried a fusible link near the junction block on the drivers side check to see if the junction block is corroded and that no wires are fried, and that all wires are tight and yours should be the same because i havean 85 as well