vx clutch switch - cruise control - mystery

[steffen707]

Originally Posted by imzjustplayin

there's actually two clutch switches.. one when you fully depress the clutch (starter interlock I guess) and one when you release the clutch. Cars today all have the switch when you fully depress the clutch, it's the one when you release the clutch that is unique to the VX/HX cars..

So has anybody figured out if the ecu operates properly without the b7 ecu pin hooked up? Also, does this pin see voltage or ground when the clutch is out?

Can any vx owner out there unplug this clutch switch and tell the rest of us what happens if its unplugged?

If it is only activated when the clutch is all the way out, you could just feed it 5 volts or ground, whichever it is suppose to see, all the time and then not worry about it.

[imzjustplayin]

Originally Posted by steffen707

So has anybody figured out if the ecu operates properly without the b7 ecu pin hooked up? Also, does this pin see voltage or ground when the clutch is out?

Can any vx owner out there unplug this clutch switch and tell the rest of us what happens if its unplugged?

If it is only activated when the clutch is all the way out, you could just feed it 5 volts or ground, whichever it is suppose to see, all the time and then not worry about it.

Well the switch is definitely used for the upshift switch, however in the service manual it mentions this switch when you're troubleshooting idle control issues so I think there is a little more to it. I don't feel it's right to ask VX owners to disconnect their switch only to have them discover they notice no difference because most VX owners don't have working switches in the first place! I've "repaired" this clutch switch before but for the purpose of fixing the cruise control. Also I'd say most VX owners don't have their cars running in tip top shape anyhow so it's hard to say that a working switch would help. Either way, better to fix or replace the switch than to just trick it.

[steffen707]

Well my civic only has 1 clutch switch, and thats when the clutch is all the way down to the floor.

So i would have to be tricking it in a way. Because the other vx one only activates when the clutch is all the way out right?

So, can somebody tell me is the b7 pin suppose to see ground or 5volts when the clutch is not depressed?

[steffen707]

As i thought about this in the shower, how would the clutch switch affect idling? If the clutch is engaged, and clutch pedal isn't depressed, the ecu wouldn't know if it was in gear, or in neutral.

I suppose it could look at the vss and clutch switch to determin if its in gear or in neutral.

[imzjustplayin]

Originally Posted by steffen707

Well my civic only has 1 clutch switch, and thats when the clutch is all the way down to the floor.

So i would have to be tricking it in a way. Because the other vx one only activates when the clutch is all the way out right?

So, can somebody tell me is the b7 pin suppose to see ground or 5volts when the clutch is not depressed?

Are you sure there is no switch there? What do you do to adjust the pedal height? Maybe you could take some pics under there.. Seems odd you wouldn't have one.

[steffen707]

Originally Posted by imzjustplayin

Are you sure there is no switch there? What do you do to adjust the pedal height? Maybe you could take some pics under there.. Seems odd you wouldn't have one.

Well my car 97 civic hatch has one clutch switch, but not 2 like the vx civic has.

[steffen707]

I checked the honda manual and on 11-94 it says "Idle Control System Troubleshooting Flowchart M/T Clutch Switch Signal D15z1 Engine. This signals the ECU when the clutch is engaged.

1. Voltage between the B7 and A26 pins should be less than 1 volt with the clutch pedal out.

2. When you step on the clutch pedal it is suppose to read about 5 volts between B7 and A26.

The one side of the clutch pedal plug goes to the pnk/blu B7 pin, and the other side is black and goes to G301 (some ground, I didn't locate that yet in the schematics).

Now i just wonder if the switch is normally open or normally closed....

I read that if you measure voltage between pnk/black on the connector and body ground with the connector unplugged from the switch and ignition on, there should be approx. 5 volts.

This makes me think that the switch is normally open when clutch pedal is up, and it closes the circuit between ground and B7 when the pedal is pressed just like in step 2 above.

So for most people that do this and don't hook up b7 to anything, it makes the ecu think the clutch is always engaged. If you grounded this wire constantly, it would make the ecu think the clutch pedal was always in the down position.

Does anybody agree with my analysis of what the manual says?

[imzjustplayin]

Originally Posted by steffen707

I checked the honda manual and on 11-94 it says "Idle Control System Troubleshooting Flowchart M/T Clutch Switch Signal D15z1 Engine. This signals the ECU when the clutch is engaged.

1. Voltage between the B7 and A26 pins should be less than 1 volt with the clutch pedal out.

2. When you step on the clutch pedal it is suppose to read about 5 volts between B7 and A26.

The one side of the clutch pedal plug goes to the pnk/blu B7 pin, and the other side is black and goes to G301 (some ground, I didn't locate that yet in the schematics).

Now i just wonder if the switch is normally open or normally closed....

I read that if you measure voltage between pnk/black on the connector and body ground with the connector unplugged from the switch and ignition on, there should be approx. 5 volts.

This makes me think that the switch is normally open when clutch pedal is up, and it closes the circuit between ground and B7 when the pedal is pressed just like in step 2 above.

So for most people that do this and don't hook up b7 to anything, it makes the ecu think the clutch is always engaged. If you grounded this wire constantly, it would make the ecu think the clutch pedal was always in the down position.

Does anybody agree with my analysis of what the manual says?

I disagree.. When the clutch is released, the switch has continuity.. A COMMON issue with this switch is that despite the clutch being released, the circuit remains incomplete (open). This was a problem for me because this same switch is used for the cruise control and if the circuit is not complete, the cruise control assumes that you've touched the clutch and therefore cannot engage the cruise control. The switch is depressed when the clutch is released and when the switch is depressed, it completes the circuit. This switch is also used as a way to adjust the clutch pedal height.

[steffen707]

Crap, you are right, the manual says to check for continuity on the 2 pins of the clutch switch with the connector unplugged and the clutch released.

So my analysis was backwards and actually.....

The switch is normally closed when clutch pedal is up, and it opens the circuit between ground and B7 when the pedal is pressed.

So for most people that do this and don't hook up b7 to anything, it makes the ecu think the clutch pedal is always being pushed.

So if you grounded this wire constantly, it would make the ecu think the clutch pedal was in the up (clutch engaged) position.

Or you could do some relay setup so that it gave you the right signal to B7 from the other clutch safety switch, if you lack 2 clutch switches.

[Mpgian]

will this 2nd switch effect lean burn?

Im still doing the final wiring on my 90 crx vx swap and this thread has me scratching my head... to add a switch or not...

also can the p07 (vx ecu) support a cruise control.... controller?