Howdy All

Got my truck back on the road a couple weeks ago. It starts good and runs good so I'm pretty happy with the results considering that it sat idle in my shop for 3 years.

But now it has developed a problem that I'm not sure of.

After the truck has been run enough to be warm if I shift into park the starter takes off. If the motor has died then the starter runs continuous trying to start the truck, but of course the power to the IP is off so it just sits there turning the motor over. It's parked back in the shop now with the battery disconnected.

I'm at a loss as to what would send power to the starter simply because I selected park at the transmission. Anybody got a suggestion?

Thanks in advance.

Ron

 

I'm guessing you have an automatic transmission? I would say try disconnecting the park/neutral safety switch on the transmission. It's also the switch that turns on the backup lights when you shift into Reverse.

I bought a replacement one at the local parts store and the POS crapped out in about 2 days. "Sorry we can't take returns on electrical components"

with the park/neutral switch disconnected you won't be able to start the truck unless you bypass the switch or jump start it on the starter solenoid. But at least it may diagnose your cranking in park problem?

Edit: I'm not 100% but if I remember correctly starter circuit is red wire with a blue tracer...
Edit Edit:.... or was it blue wire with red tracer?? oh bugger I must be getting old....
Edit Edit Edit: It's the color of the solenoid activation wire on your starter solenoid

 

Reverse circuit power going to the starter trigger wire when shifting gears sounds like a very good place to look to me as well.

The neutral safety switch/reverse light switch would be the best location for that to happen.

Right after that, I think the next place to look would be the wires on the ignition switch under the dash.

Red/lt. blue is the starter relay trigger wire.

 

Does the starter quit spinning when you pull it back out of park, or is it trying to start all the time.

 

First to answer a previous question, this is the original C6.

As I drive to a point that I want to stop and park, if I select Park at the collumn the starter is triggered. If the motor is still running it grinds until the motor stops then it just continues to spin the stater. I have, so far, been able to get it to stop spinning the starter by forcing the gear selector as far as it will go to the Park end of the selector. From previous posts I'm wondering if the neutral switch is adjustable which might solve the gear selector problem but would not explain why power is being sent to the starter solenoid.

This sounds to me like more than one problem showing itself.

Ron

 

The wire from the key start position runs down to the neutral safety switch, if the selector is in neutral or park, then power from the key switch goes through the safety switch to the starter relay.

Does the C 6 not also use the neutral safety switch as the reverse light switch?

If it does, power is going to the reverse part of the switch when the key is on, and on to the backup lights when the lever is in reverse.

If the switches are in different locations, you still have power going to both switches in two seperate wires, and power leaving in two seperate wires.
If the shifter linkage touching the wires anywhere shorting reverse power to the start circuit?

Since start power only goes down to the neutral safety switch when you turn the key to start, the power going to the starter relay has to be coming from another circuit.

Thinking about what circuits run power down there, tank selector valve, reverse lights, brake lights and battery electric brake power if you have a 7 blade trailer socket.

There are a couple hot wires near the shifter linkage/steering column where it goes through the firewall, is the linkage shorting a wire there?

Also power down to the 4x4 switch in the transfer case for the dash 4x4 light, which may have enough power going through the light bulb to close the start relay.

Right now that is the only circuits I can think of that would have power near the shift linkage that could get shorted over to the start wire.

 

Thanks Dave this will all be very helpful.

Is there a point to point test that I can run on the Neutral Start Switch? I expect that the ignition and the starter relay should be pretty straight forward testing but I'm not familiar with the NSS.

Thanks

Ron

 

The outside of the neutral safety switch on a C6 is metal, the back side is plastic. The switches back side is held on with bent over tabs from the metal and after years may have corroded off allowing the switch to flex strange and the inner "Wipers" fall out of place.

Reverse and starting safety are all bundled into this 1 switch.

There is a small amount of adjustment, but I don't believe adjusting it will fix the cranking issue as it sounds as if the switch has just gone bad entirely. If you follow the wires off the switch (drivers side of the transmission right behind the shift linkage) they will travel back to a clip on the extension housing, then across the cross member and onto the inner drivers frame rail. On that inner drivers frame rail/cross member area you will find it's electrical connector. Disconnect it and put the truck in Park, if it cranks your problems are elsewhere. If it sits quietly in park it's the switch. They're not too bad to replace. 3/8" socket for the 2 switch bolts and I believe a 7/16" or 1/2" for the kick down lever nut. Then a big flat blade screwdriver to pry the switch off the shift selector shaft.

Best of luck!

 

That all makes good sense, thanks for the help.

Ron