Mystery of the Clicking Solenoid - M1009

[bigredlab]

Well its that type of year, getting dark early and getting stormy.

After leaving my lights on (for several hours), my M1009 wont start. I turn on electrical power and the solenoid has this wierd clicking sound. Battery only shows middle to top of yellow.

Here are the facts:
- Tried to jump the M1009 for over 2 hours, no joy. Even AAA couldn't do it.
- Had batteries checked at local auto parts store, fully charged
- changed out solenoid with backup, no luck
- Starter system has "civilian" mod
- Wait light is intermittant (sometimes it comes on, sometimes not)
- No blown fuses

Where else can I check?

Please help!!

 

[Radioshop]

Got a volt meter?

 

[bigredlab]

yes

I forgot to add this info

Voltage on the battery side of the solenoid is variable. sometimes it is 8v sometimes 12.

 

[Blood_of_Tyrants]

Your voltage should be around 13.5 vdc on a good battery. Check the battery ground at the block. Also make sure all battery connections are good.

 

[bigredlab]

I am having my son recheck all of the voltages at all of the connection points and will post as soon as I get them.

 

[bigredlab]

Just got the voltmeter readings from my son.

Battery side of the Terminal Bus (triangle on firewall) 12.5 (drops to 11.5 with key on)

Solenoid side of Terminal Bus 12.5 (drops to 11.3 with key on)

Soleniod side A [connected to terminal bus) : 12.5

Soleniod side b : 1 volt (clicking)

This is the same for both solenoids that I have tried.

What else can I check?

 

[southdave]

starter relay maybe? does the 12V system use a relay still? got 24v on the brain , mine has been a real education ,or could just be ign. switch

 

[Blood_of_Tyrants]

Can you turn the engine manually?

Try this: Take a screwdriver and short the small control wire to the battery wire on the starter solenoid. If it cranks, you have a problem with the voltage to the solenoid control. If it doesn't crank, you have a problem with the heavy gauge wiring from the battery.

 

[bigredlab]

I've never done that before, but OK.

Just to make sure I understand correctly, short the solenoid on the top of the starter. I do this with the key on.

Am I correct?

 

[fireman9]

When your taking you voltage readings what are you using for a ground? The body or battery? If it's the body check your ground connections at the block and inspect the negitive cable for a small pigtail to sheet metal ground on the radiator support. Also check for a ground strap in the rear of the cylinder head to the firewall. They could be dirty/corroded.

You should have better than 12.8 volts on a fully charged 12 volt battery. Also check for a bad/corroded fuse link wire at the starter motor. It will be a small gauge wire connected with the large battery positive cable at the starter solenoid.

 

[Blood_of_Tyrants]

I've never done that before, but OK.

Just to make sure I understand correctly, short the solenoid on the top of the starter. I do this with the key on.

Am I correct?

Yes, short the big battery terminal to the solenoid coil wire. That will bypass all the starting circuitry. The ignition switch does not need to be on just to crank it.

 

[fireman9]

Yes, short the big battery terminal to the solenoid coil wire. That will bypass all the starting circuitry. The ignition switch does not need to be on just to crank it.

While this should make it crank, It won't fix the problem.

 

[4bogginchevys]

So...was your ignition on? (for hours with headlights)

 

[91W350]

While this should make it crank, It won't fix the problem.

It will tell him if his starter is functioning properly and he can look elsewhere. We all carry different mechanical histories and while some of us work off of meters, some of us never had that luxury and work off of the process of elimination.

I can remember having a heated conversation with my father over me striking the bottom of his starter with a hammer when his big block would not start. He, in not so kind words, told me a hammer was not going to fix his starter. I agreed, but it did let me get the truck started and driven home where my tool boxes, jack stands, jacks, solvent tank, vise etc... were. I would much rather pull the starter at home than in the xyz parking lot.

Smae thing for slapping the bottom of a fuel tank with your hand to get the electric pump going on GM vehicles. I would rather pull that tank in my garage. I would also rather drive the vehicle there than tow it.

 

[fireman9]

While I have no problem hitting a starter with a hammer or for all you power window people with it stuck down in the rain (HOLD UP BUTTON, BEAT ON DOOR PANEL).
It would seem that his truck has had many electrical problems in the past. Search for his other posts. I doubt that leaving the headlights on killed anything other then the batterys ( I done it many times over the years myself) but It could have an effect on poor connections and hi resistant shorts and bad grounds, which could also explain why he's getting such large differences in voltage readings key on vs key off.
I have seen the all to common GM truck not start due to a bad ground connection at the motor mount or altenator bracket. I've seen many starters changed for that reson too, and not to mention burnt throttle cables, melted speed cables, and bad U-Joints all from the engine trying to get a good ground while cranking.
I'm don't want to offend anyone who can repair a truck in the bush but sometimes you do need to go a little further.
As far as newer mechanics most shouldn't be called that anymore most garages hire parts changers....They just keep swapping stuff till it works and never find out why it broke in the first place, most repairs are short lived and these people should be shot. It's giving the hole industry a bad name.

 

[Blood_of_Tyrants]

While this should make it crank, It won't fix the problem.

No, but it will help eliminate the solenoid as a problem.

 

[Blood_of_Tyrants]

Smae thing for slapping the bottom of a fuel tank with your hand to get the electric pump going on GM vehicles. I would rather pull that tank in my garage. I would also rather drive the vehicle there than tow it.

You have done that, too? The worst POS I ever owned was a 1979 Chevy Monza. For no reason at all the fuel pump in the tank would stop working and the care wold stop running. I would slap the bottom of the tank to get it running again. The best day I ever had when I owned that car was when it caught afire and the insurance paid off.

 

[fireman9]

No, but it will help eliminate the solenoid as a problem.

No it will only eliminate the wiring to the solenoid itself. If you jump the large battery term to the large starter motor term with a "BIG" screwdriver (INSERT WELDING GLASSES HERE) then it will eliminate the solenoid.

The solenoid is just a large relay that also extends the starter drive to the flywheel, Shorting the large connectors will mark the starter motor run but it won't crank the engine.You may still have a bad solenoid but a good motor.Solenoids are cheap, Starters not so much.
s

Simple GM starter wiring diagram the 6.2 doesn't use the "I" term. Its hot while cranking to supply the coil of gassers full 12 volts during start up.

 

[Blood_of_Tyrants]

No it will only eliminate the wiring to the solenoid itself. If you jump the large battery term to the large starter motor term with a "BIG" screwdriver (INSERT WELDING GLASSES HERE) then it will eliminate the solenoid.

The solenoid is just a large relay that also extends the starter drive to the flywheel, Shorting the large connectors will mark the starter motor run but it won't crank the engine.You may still have a bad solenoid but a good motor.Solenoids are cheap, Starters not so much.
s

Simple GM starter wiring diagram the 6.2 doesn't use the "I" term. Its hot while cranking to supply the coil of gassers full 12 volts during start up.

First, I am an electrical engineer. I know what a solenoid does. I have also worked as an electronics technician and an aviation electrician. I have plenty of experience in troubleshooting electrical problems.

There will not be that big of a spark because the only current you are drawing through the solenoid is from the battery to the coil of the solenoid. Finally, the solenoid for a 6.2L GM engine is EXPENSIVE. I think I found the cheapest at $170.

Also, there is an interposing relay between the ignition switch and the solenoid. The original purpose was to switch 24vdc to the coil of the starter solenoid. If you have converted the truck to 12vdc, then this circuit can be bypassed as it no longer serves a purpose. Simply remove the relay and splice wires 3 RED-2Y to 3 PPL-6.

 

[bigredlab]

Thanks to everyone who has posted on this thread. As my past posts can attest, this M1009 has some electrical issues. I am slowly working through them replacing wires, etc. Unfortunately, I am not 'electrically inclined'.

Mystery Solved!!

It turned out that the forward battery was bad. Both of the batteries were 'load tested' at the Auto parts store (where we purchased the battery) and showed good. However, I guess the load test wasn't stressful enough. An electrical engineer friend of mine (who is also a good mechanic) walked me through how to test, step by step.

The rear battery when load tested in the vehicle maintained its charge at around 12.5v. The front battery started at 12.1v and would drop to 6v when the ignition was turned to on (not to start). When turned to start it would drop to 4v. Forced the issue with the Auto Parts store and got the battery replaced. Voila! works like a charm.

Once again, thanks to all for the help.

BTW, never got to the BIG Screwdriver test. I don't know how I would do it, though, as I couldn't hardly touch it with my hand (much less a big screwdriver).