Clutch safety switch and cruise control

[Upstate Saturn]

I'm getting some squeaking from my clutch pedal in my '01 SL2, and figure while I'm contorted into a pretzel in the footwell lubricating the pedal, I might as well disable the asinine clutch safety switch at the same time. (aka the "Too Moronic to Drive Switch") In reading up on how to disconnect it, one thread talked about how it would also disable the cruise control, but it didn't really give any details about how the cruise control is tied in. Of course I can't find the thread again, but that was the only one out of several I read that mentioned any tie between the clutch safety switch and cruise control.

Will cruise control no longer work if I put a jumper on the safety switch? I plan to use a 14 gauge wire with two male terminals to keep the circuit closed all the time, and I'll use crimp connectors and cover them with heat shrink, per info from other posts.

[trottida]

I'm not 100% sure on how the switch works but I can assume that when you engage the clutch while the cruise is on, the safety switch is likely also responsible for disabling the cruise control. With that in mind I would speculate the cruise module is looking for the circuit to be open and if permanently wired closed, cruise will not engage. Thus the cruise control is effectively disabled. The starter circuit (BCM?) on the other hand is looking for the circuit to be closed before it will power the starter. Does that help?

[madpogue]

Your car doesn't have a clutch switch for the cruise control. When you DISengage the clutch with the cruise engaged, you'll notice the RPMs rise momentarily. That's the PCM trying to maintain the speed, but of course with the clutch disengaged it can't. It detects that the relationship between the RPMs and the speed no longer correspond to one of the gear ratios of the car's transmission, and interrupts the cruise. It's effectively a "software clutch switch". Probably cost five or six digits of dollars to program that into the PCM, but that one time programming cost is way cheaper than a million 50-cent switches.

This started with the gen-2 cars in '96. The '91-'95 cars had a physical clutch switch to disengage the cruise, but it was completely separate from the clutch SAFETY switch for the starter circuit. For reasons which should be obvious when you picture the system in your mind, the cruise interrupt switch was triggered at the TOP of the pedal travel, and the starter safety switch is triggered at the BOTTOM of the pedal travel.

So way too long story short, bypassing the clutch starter safety switch will have zero impact on the cruise control, in your car or any generation of S-Series.

The starter circuit, BTW, is completely electromechanical. It has NO interface with the BCM or PCM.

[OldNuc]

The foot on the floor interlock switch is located on the firewall just above the bend in the pedal shaft. Disconnect the connector and take a pair of F2 spades, these are the 1/4" ones with a 1" to 2" long piece of #14 wire crimped onto the 2 spades and stuff the spade jumper into the connector. Tuck neatly out of the way and do not let it short to ground. All fixed forever. The spade crimp connectors are at the parts store and the blue ones will work with #14 wire. You will need a crimp tool which will also take care of insulation removal. There is a rubber shield behind the rug that you can stick the connector with jumper and it will be just fine back there. No huge ball of electrical tape required.

[OldNuc]

Originally Posted by madpogue

The starter circuit, BTW, is completely electromechanical. It has NO interface with the BCM or PCM.

Not any more with the new cars, all electronic until the high current solenoid is energized.

[madpogue]

Originally Posted by OldNuc

Not any more with the new cars, all electronic until the high current solenoid is energized.

Yet another reason to be grateful that the NEWEST motor vehicle in our driveway is contemporaneous with the Macarena.......

[OldNuc]

I am not impressed with the idea of proprietary software, all digital serial links, no emergency analog override capability and the list goes on. Experience with the gen-3 Saturn gives a clue as to how all this electronics is going to hold up over time. Figure 10 years or so and it is done.

[Upstate Saturn]

Thanks, everyone, for the replies.

Originally Posted by OldNuc

No huge ball of electrical tape required.

OldNuc, you know or suspect too much! Back in the day when I was a sweet young thing, I took my first car, a '67 VW squareback, to my first vehicle safety inspection. I was able to drive into the service bay, but then smoke began to pour out of the ignition switch, and it had to be pushed back out and towed home, so mortifying to a 16 year old girl!

My older brother got me a new junkyard switch, showed me how to make a butt splice, and told me to match color to color on all the other wires. So I did, but I used so much electrical tape that there was no way to stuff the wiring back into the steering column. But I was so pleased when it started and didn't catch on fire! I drove it for a long time with the wiring hanging out of the column....

[OldNuc]

The connector fits nicely under the top edge of the rug so it is not under foot or pedal and the rubber edge protector keeps it off the sheet metal fire wall. It is now far enough up there that you can not step on it. Works very well. Idiot switch bypassed about 15minutes after bringing car home for the first time. The rubber holds the firewall insulation down against the floor pan and covers a razor sharp edge. Connector with jumper on top of rubber and under edge off rug - done.

I have spent way too much time unwrapping cheap electrical tape that would have been adequate for insulating a 3000A 4160V tap from an automotive 20A 12V circuit.

Takes longer to make the jumper than to install it. Use a small screwdriver to push in the connector latch and simultaneously push it out of the switch.

[madpogue]

Originally Posted by OldNuc

Figure 10 years or so and it is done.

For some, ten years constitutes the "break-in" period. My IDI just turned 30. After the electromagnetic pulse pole shift zombie apocalypse, it will still go down the road past the bicycles and ox-carts.

Originally Posted by Upstate Saturn

My older brother got me a new junkyard switch, showed me how to make a butt splice, and told me to match color to color on all the other wires. So I did, but I used so much electrical tape that there was no way to stuff the wiring back into the steering column. But I was so pleased when it started and didn't catch on fire! I drove it for a long time with the wiring hanging out of the column....

Your brother should have given you one of these: http://www3.telus.net/bc_triumph_registry/smoke.htm .

(BTW, the last person here who also owned a Squareback was a self-proclaimed former Saturn tech, who sure knew his stuff, but made NO friends here. Let's just say he did not share your cheery demeanor....)

[Upstate Saturn]

Originally Posted by madpogue

Your brother should have given you one of these: http://www3.telus.net/bc_triumph_registry/smoke.htm .

ROFLMAO!!!

Here's one of my favorite parts from the link above:

"Have you inadvertently let the smoke out of the wires on your classic British car? This, then, is the solution to your problem!

Here is presented for your perusal one Lucas Replacement Wiring Harness Smoke kit, P/N 530433, along with the very rare Churchill Tool 18G548BS adapter tube and metering valve... The smoke is metered, through the fuse box, into the circuit which has released it's original smoke until the leak is located and repaired. The affected circuit is then rectified and the replacement smoke re-introduced."

[OldNuc]

FYI the ignition switch in the Saturn is manufactured by Lucas, King of the Road, Prince of Darkness.

You will find multiple threads of ignition switch failure leading immediately to steering column immolation.

[trottida]

Originally Posted by madpogue

Your car doesn't have a clutch switch for the cruise control. When you DISengage the clutch with the cruise engaged, you'll notice the RPMs rise momentarily. That's the PCM trying to maintain the speed, but of course with the clutch disengaged it can't. It detects that the relationship between the RPMs and the speed no longer correspond to one of the gear ratios of the car's transmission, and interrupts the cruise. It's effectively a "software clutch switch". Probably cost five or six digits of dollars to program that into the PCM, but that one time programming cost is way cheaper than a million 50-cent switches.

Thanks, now I'm educated! It would be nice to have that switch at the top of the pedal so the rpms didn't take off like they do. That really bugs me. I didn't recall that happening on my original 92 SL2 MT; I assumed that it probably did and that I had forgot over the 11 year gap where I didn't have a manual transmission S Series.

[alordofchaos]

Originally Posted by trottida

I didn't recall that happening on my original 92 SL2 MT; I assumed that it probably did and that I had forgot ...

Nope, the early cars (through 1995) had a real clutch switch. The "electronic" version appeared in 1996. So your memory is not failing you.

[J N Winkler]

Originally Posted by OldNuc

FYI the ignition switch in the Saturn is manufactured by Lucas, King of the Road, Prince of Darkness.

In the European Union, local assembly requirements are so strict that when Nissan broke into the UK market in the mid-1980's, it did so by shipping CKD kits from Japan to a new factory near Newcastle. (At the time, cars destined for the US market were completely assembled in Japan prior to shipment to the US.) Originally Japanese parts were shipped from Japan, but over time more and more components were locally sourced, including alternators from Lucas. Japanese cars never acquired the reputation for reliability in Britain that they did in the US; funny how that works.

[OldNuc]

Anyone who has ever owned a British automobile of just about any vintage is well aware of the reliability, or lack thereof.

[Upstate Saturn]

Originally Posted by OldNuc

FYI the ignition switch in the Saturn is manufactured by Lucas, King of the Road, Prince of Darkness.

You will find multiple threads of ignition switch failure leading immediately to steering column immolation.

Where's the handiest place to stash the fire extinguisher?

[OldNuc]

Train yourself to remove the keys from the ignition before locking all doors and then just cut the green and black wires for the key minder. Then when the switch fails you will get some other weird symptoms but no smoke as no ground and no feed to the chime low input.

[fdryer]

Upstate Saturn, according to service manual descriptions, cruise control (when enabled) and engaged, is disengaged by pressing either the brake or clutch pedal. The clutch safety switch is used for dual purposes, to prevent starting without pressing the couch pedal and to disengage cc. When you bypass this switch you effectively prevent cc from disengaging and can start in or out of gear. Cruise control will work but won't disengage with a bypassed clutch switch. The brake pedal switch or manually turning off cc are the only two ways to disengage cc. Be aware of this. You may be in for a rude awakening when you use cc and step on the (bypassed switch) clutch pedal and not find the engine rpm dropping. You may find the opposite - the engine revving since speed drops and cc detects this and tries to raise engine rpm's to maintain speed; a runaway engine unless you are alert and either press the brake pedal or turn off cc.

Either replace or repair whatever is causing you to contemplate bypassing this clutch safety switch.

[OldNuc]

Originally Posted by fdryer

Upstate Saturn, according to service manual descriptions, cruise control (when enabled) and engaged, is disengaged by pressing either the brake or clutch pedal. The clutch safety switch is used for dual purposes, to prevent starting without pressing the couch pedal and to disengage cc. When you bypass this switch you effectively prevent cc from disengaging and can start in or out of gear. Cruise control will work but won't disengage with a bypassed clutch switch. The brake pedal switch or manually turning off cc are the only two ways to disengage cc. Be aware of this. You may be in for a rude awakening when you use cc and step on the (bypassed switch) clutch pedal and not find the engine rpm dropping. You may find the opposite - the engine revving since speed drops and cc detects this and tries to raise engine rpm's to maintain speed; a runaway engine unless you are alert and either press the brake pedal or turn off cc.

Either replace or repair whatever is causing you to contemplate bypassing this clutch safety switch.

Absolutely not true. That is incorrect for any Gen-2 or Gen-3 car.


Go look at the electrical wiring diagram.