Car wont turn over after Clutch Master Cylinder replaced

[larry bud]

1986 Vette, been running fine, but I noticed that the clutch was squishy and discovered the clutch master cylinder was leaking, so I bought a new one. I've had this car since '92 and have replaced this part twice before, it's no biggie.

Unhooked the neg battery terminal, remove the clutch master cylinder, put the new one in, bled it, buttoned everything up, and now the car won't even turn over.

At first I thought it might be the clutch switch on the pedal, where it would think the clutch wasn't depressed, but that's not it. I didn't disconnect anything under the hush panel, and I double (and triple) checked to make sure nothing came unplugged, specifically the connection for the VATS for the key.

I'm at a loss as to what I might have done.

 

[ecss]

Wnen you turn the ignition to start, do you hear a faint click behind the Driver Info display area?

That will tell you if the Starter Enable relay is being grounded by the Decoder module.

If no faint click sound, short Pin A to B on the diagnostic connector above the drivers right knee.

Turn the ignition On and see if code 46 is stored which indicates the key pellet
is not being read correctly and a time out delay will start where the starter will be disabled.

This time out can not be reset by disconnecting the battery.

If you do hear the click, disconnect the connector at the
clutch pedal switch. Measure the voltage on the Dark
Green/White wire. Should be 12 volts when the ignition
key is in the Start position. The 12 volts comes from the
Starter Enable Relay when it closes.

If you do measure 12 volts on the Dark Green/White wire
take a paper clip and short the two wires together to bypass
the clutch switch. (Dark Green/White wire shorted to the Purple wire).

Make sure the trans. is in neutral or the clutch pedal is depressed so
the vehicle doesn't move if the starter does engage.

The Purple wire goes to the Starter Solenoid. So if you have
12 volts on the Purple wire the solenoid should engage the starter.

Here's the schematic.



Also if the starter enable relay doesn't engage (no faint click)
you need to remove the Driver Information panel to gain
access to the Starter Enable relay where you can narrow
down the problem by taking voltage measurements at the
relay.

Here's a picture of the Starter Enable Relay labeled #2
in the picture.

 

[larry bud]

Thank you for a detailed explanation. I'll run this down and give my result.

 

[vetteoz]

At first I thought it might be the clutch switch on the pedal, but that's not it.

Have you confirmed the clutch safety switch is set correctly and still working ,
seeing that the only thing you played with before the problem was R/R the M/C ; possible you knocked the clutch safety switch out of adjustment ?

 

[larry bud]

Well, this was interesting. I narrowed it down to the clutch safety switch. I removed it, tested it, and it worked fine. Put it back in (no easy feat), and the arm of it wouldn't move far enough to close the switch.

The only "adjustment" that there is on it is to bend the wire that connects the pedal to the arm on the switch. I was able to bend it to effectively make it shorter. But none of this makes sense to me, since there truly is no "adjustment" for the switch. The switch itself has a tab on it, and a bolt, so it's held in place in 2 spots, and cannot be rotated.

Another little factoid is that when I pulled the dash apart, I saw a couple of extra fuses behind the IP, one of which was blown (for the cold start injectors). Seems crazy to me that they stuck a couple of fuses behind this panel.

 

[ecss]

Sounds like you used the Bubba method to adjust the
clutch safety switch.

Most of moved out of adjusment when you disconnected
the push rod.

The manual says there is an adjustment block. I don't see
a picture of it the service manual. :ugh

Clutch Operated Start Switch Paragraph 5.

Also posted the diagram for the cold start injector circuit.