Clutch safety switch wiring for manual swap.

[VictoryRed]

Whats the best way to do this I should finish my manual swap this weekend and i want to wire a switch in somewhere either under the dash to double as anti theft or just one on the firewall that presses down when the clutch is in. I need to know what color wires im looking for or a wiring diagram.

 

[Scooterwrench]

Millions of vehicles were built before the advent of the clutch safety switch.

 

[Road Trip]

Whats the best way to do this I should finish my manual swap this weekend and i want to wire a switch in somewhere either under the dash to double as anti theft or just one on the firewall that presses down when the clutch is in. I need to know what color wires im looking for or a wiring diagram.

Sir,

Help us help you. The wiring varied over the years, so if you could tell us what year vehicle you are working
on, we will know which books to use in answering your question.

 

[Scruffy]

The factory clutch safety switch is a ticking time bomb plastic pos. Next time mine breaks I’m deleting it via a simple jumper wire. 99 K3500 with an NV4500.

 

[VictoryRed]

Sir,

Help us help you. The wiring varied over the years, so if you could tell us what year vehicle you are working
on, we will know which books to use in answering your question.

It should have put it in the post automatically 99 tahoe 5.7 4dr LT

 

[VictoryRed]

Millions of vehicles were built before the advent of the clutch safety switch.

Well basically im forced to put one in if i wanna drive my manual swap so it has to happen.

 

[Road Trip]

Whats the best way to do this I should finish my manual swap this weekend and i want to wire a switch in somewhere either under the dash to double as anti theft or just one on the firewall that presses down when the clutch is in. I need to know what color wires im looking for or a wiring diagram.

Here's the wiring diagram you requested from the '99 Factory Service Manual.

What you used to have w/your automatic: Circuit #806, Purple wire between CRANK fuse in IP fuse block to Transmission Range Switch
on side of transmission. (See attached pic of TR switch & also Connector pinout.)

You must be registered for see images attach

According to the General's wiring diagram, you now need to re-route that input wire from the original TR switch that was on the side of the auto
to a Clutch Pedal Position Switch under the dash in the cab.

NOTE: The input wire is purple, but changes to a Purple wire w/white stripe (Circuit #1035) on the output side of the switch, which as
the diagram shows heads back to the Underhood Fuse Block so that it can power the control side of the Starter Relay.

Fortunately the circuit is pretty straightforward:

* If Automatic, no starter cranking allowed unless shifter is in the Park or Neutral positions.

* If Manual, no starter cranking allowed unless clutch pedal is fully depressed.

It's purely safety related, and protects against driver error during engine cranking leading
to loss of control & possible serious injury to bystanders.

Good on you for wanting to make your swap as safe as a factory installation.

Hope this helps.

Cheers --

 

[VictoryRed]

Here's the wiring diagram you requested from the '99 Factory Service Manual.

What you used to have w/your automatic: Circuit #806, Purple wire between CRANK fuse in IP fuse block to Transmission Range Switch
on side of transmission. (See attached pic of TR switch & also Connector pinout.)

You must be registered for see images attach

According to the General's wiring diagram, you now need to re-route that input wire from the original TR switch that was on the auto
to a Clutch Pedal Position Switch under the dash in the cab.

NOTE: The input wire is purple, but changes to a Purple wire w/white stripe (Circuit #1035) on the output side of the switch, which as
the diagram shows heads back to the Underhood Fuse Block so that it can power the control side of the Starter Relay.

Fortunately the circuit is pretty straightforward:

* If Automatic, no starter cranking allowed unless shifter is in the Park or Neutral positions.

* If Manual, no starter cranking allowed unless clutch pedal is fully depressed.

It's purely safety related, and protects against driver error during engine cranking leading
to loss of control & possible serious injury to bystanders.

Good on you for wanting to make your swap as safe as a factory installation.

Hope this helps.

Cheers --

Thank you this is exactly what I needed.

 

[VictoryRed]

Here's the wiring diagram you requested from the '99 Factory Service Manual.

What you used to have w/your automatic: Circuit #806, Purple wire between CRANK fuse in IP fuse block to Transmission Range Switch
on side of transmission. (See attached pic of TR switch & also Connector pinout.)

You must be registered for see images attach

According to the General's wiring diagram, you now need to re-route that input wire from the original TR switch that was on the auto
to a Clutch Pedal Position Switch under the dash in the cab.

NOTE: The input wire is purple, but changes to a Purple wire w/white stripe (Circuit #1035) on the output side of the switch, which as
the diagram shows heads back to the Underhood Fuse Block so that it can power the control side of the Starter Relay.

Fortunately the circuit is pretty straightforward:

* If Automatic, no starter cranking allowed unless shifter is in the Park or Neutral positions.

* If Manual, no starter cranking allowed unless clutch pedal is fully depressed.

It's purely safety related, and protects against driver error during engine cranking leading
to loss of control & possible serious injury to bystanders.

Good on you for wanting to make your swap as safe as a factory installation.

Hope this helps.

Cheers --

So basically I am re routing the wire from the transmission range switch to a switch that ties into the clutch pedal and then that gets connected to the yellow correct?

 

[Road Trip]

So basically I am re routing the wire from the transmission range switch to a switch that ties into the clutch pedal and then that gets connected to the yellow correct?

If I understand your comment correctly, that describes part of the overall circuit. Let me
walk us through the entire safety circuit, from the fuse that supplies the power all the
way to the Starter relay. (Note: The following is based upon the fact that you started
the project with a '99 K1500 5.7 Vortec 4L60-E.)

****

For what you are trying to do, we will be starting at the output of Fuse #8 (CRANK)
located in the IP (Instrument Panel) fuse block.

* With your original automatic, the purple wire leaving fuse #8 exits the cab via Pin E1
of C100. In the engine bay, this purple wire continues down to the TR switch on the
side of the automatic. From this switch, the Purple w/white stripe wire goes back up
to the Underhood Fuse Block and feeds into the control side of the Starter Relay switch.

* With your newly installed 5-speed manual, you are now going to take the purple wire from
the output of the aforementioned CRANK fuse, and use this to feed into the CPP (Clutch
Pedal Position) switch that's installed in such a way so that this switch closes when the clutch
pedal is fully depressed by the driver.

On the output side of your clutch pedal switch you are *now* going to exit the cab via
pin E1 of C100 and on to the control side of the Starter Relay inside the Underhood Fuse Block.
(Bonus points for re-using the PPL w/WHT wire that was between the Starter Relay and
the TR switch on the 4L60-E. Now the PPL/WHT wire will go from the Starter Relay
to C100, Pin E1, and inside the cab up to the output side of the CPP switch.)

Essentially the original wiring is from the CRANK fuse in the cab > C100 > TR switch > Starter relay in Underhood Fuse Block.

What you will end up with is: CRANK fuse > CPP switch > C100 > Starter relay in Underhood Fuse Block.

As for exactly what the CPP switch you want looks like, I didn't find a good illustration in the Factory Service Manual,
so I went over to Rock Auto and this is what they had to share:

You must be registered for see images attach

(Here's the LINK to go to this page on Rock Auto: LINK)

Disclaimer: Unfortunately my '99 chore truck has a 4L80-E in it, so I can't look under my dash
and 1st-person verify that this listing is correct. On the other hand, possibly someone else
with a standard in a matching GMT400 can jump in here and share what they've got?

****

Hopefully this clarifies the wiring diagram for you. I mention all this because my expectation
is that the Yellow wire feeding into the CRANK fuse (from the Ignition Switch) will remain in
place and unchanged. It's the output of the CRANK fuse (PPL) that will be re-routed to the
new Clutch Pedal Position switch. And of course from the CPP switch the PPL/WHT wire out
to the Starter Relay via C100.

If you make all that happen, then (only) when you depress the clutch pedal all the way (with
the key in the Start position) will the starter begin to crank the engine over.

If you have any further questions then don't hesitate to ask.

Hope this helps --

EDIT: I added the C100 Connector Face / Pinouts so that you can use them for reference while rewiring.