1993 intermittent no start

[Dvldog8793]

Howdy
Merry Christmas!
My son's 1993 6.5 manual just today would not turn over.
Clutch in, key on- all the dash lights come on.
Turn the key to start, nothing.
Jumped the clutch safety switch. Nothing.
Checked voltage at the switch and found none.
Hooked up and pull started with NO problem, ran fine.
Ideas?
Thanks!

[Yukon6.2]

Merry Christmas
Bad connection is the first thing i would look for starting with the trigger wire for the solenoid,then the main power wire.You can try to trigger the solenoid with jumper from a + source.
Then the starter,how old is the starter? The brushes could be wore out and one isn't making contact any more.The surfaces on the contacts in the solenoid could be arced and rough not making contact anymore,i have taken them apart and filed the contacts smooth and flipped over the disc inside to get a starter to work again.

[JohnC]

I recall there are problems with the ignition switch itself that can result in no trigger to the starter motor.

[Robyn]

You may want to check for 12V at the starter solenoid terminal.

Not too hard.

Jack up rig and block..Remove RH front tire/wheel
Remove rubber splash flap in the fender well.

The starter wiring is all right there within easy grasp.

If you have 12V at the solenoids small wire when key is turned to start then the starter is KAPUT.
Can be just the solenoid or the motor.
Also try whacking the starter with a hammer when the key is turned to start.

Quicky check :D


Also...with the access open in the wheel well you can easily get to the starters front hanger bracket real easy...

[Dvldog8793]

Howdy
OK- So we thought maybe the truck fixed itself, NOPE!
Had to push start twice yesterday.
New things that we found/checked:
- Starter and all connections down below are good
- Starter signal wire from starter to the back of the block is good
- Ignition seems to work with everything but making the truck start

- Currently we spliced into the signal wire from the starter at the back of the firewall and ran a 12v wire to tractor start button inside the cab and it works fine

Questions-

Can anybody tell me how the clutch safety switch works in this truck?

Or is there an ignition relay someplace?

Is it a direct in line switch or does it go to a relay someplace or go through the "ecm"

We are having trouble locating a wiring schematic for this particular truck.

Thanks !!!!!

[Robyn]

Clutch safety switch interrupts the 12 v to the solenoid.

Try bypassing the switch and see if the gremlin is vanquished.

The fact that you can jump the solenoid and things work takes us to the circuit from the ignition switch to the solenoid.

Ignition switch or the clutch switch are the prime suspects.

The linear type ignition switch is very possibly worn out.

Jump the clutch switch and if the fault is still there then the ign. sw is your issue.

Pretty easy to drop the column down and stick in a new switch.

They fasten to the top of the column with a couple screws/nuts.

One thing you can try is to get the thing to where it will not engage the starter and the with the key held to the start position thump the steering wheel some good ones and see if the jarring will get things to go.

If this trick does it then the ign sw is the issue.

Good luck

[Dvldog8793]

Thanks Robyn!
Forgot about the linear switch....:rolleyes:
I have replaced this a couple times on other trucks, amazing how quickly we forget!
When we jumped the Clutch switch, it had no effect and there was no power to the switch....so that would be the Linear Switch.
Thanks!