Switches on brake pedal - The 1947 - Present Chevrolet & GMC Truck Message Board Network

scsindust · 08-17-2009, 09:30 PM

I have a brake light switch that has the cruise control cancel in it. Next to that switch is another switch that has what looks to be a vaccuum line attached to it. This vaccuum line hooks into the cruise control module. What is it for, if there are wires for the module going to the brake switch too??

glock35ipsc · 08-17-2009, 09:37 PM

Probably has something to do with disengaging the torque converter clutch (TCC).

scsindust · 08-17-2009, 09:41 PM

I guess i should have said that the truck originally came with a TH400, so there was no lockup to start with.

ont_guy_38 · 08-19-2009, 11:57 AM

one of those switches are for the electric kickdown if you have a turbo 400

Driveway Dreams · 08-19-2009, 12:02 PM

kickdown on the brake pedal?

ont_guy_38 · 08-19-2009, 12:12 PM

LMAO!!!!!!!!...my god hope I dont get the gas and brake mixed up when I,m driving sorry guys a brain fart is the only explanation i got

powerdriver 1958 · 08-19-2009, 12:34 PM

the vac switch is a Vacuum bleed for the cruise control to drop the cruise off,did have a cruise control go haywire and would not shut off but the vac switch on the pedal shut it down when i hit the brakes

Driveway Dreams · 08-19-2009, 12:34 PM

Brain fart.

Crazy cruise control is scary.

scsindust · 08-19-2009, 09:08 PM

Ok, the vacuum line goes to the CC, so then what do the gray & gray/black wires go to on the top of the brake switch? I tested these leads, and they are normally closed, so do these got to the CC too? I would love to disconnect the gray wires and use the switch for the TCC lockup release.

powerdriver 1958 · 08-19-2009, 10:55 PM

yeah wires are CC

glock35ipsc · 08-20-2009, 11:58 AM

Can't you just tap into them to use the same leads for the TCC?

scsindust · 08-20-2009, 03:09 PM

That's what i wanted to do, but there isn't 12v going to the switch when the CC is off, so I'd have to get rid of the CC to use the switch which I think I am going to do. I only use CC on long trips, so oh well, bye CC.

glock35ipsc · 08-20-2009, 03:39 PM

My 85 has two switches, and came equipped from the OEM with a lock-up TH350C and cruise.

You need ACDelco part number D850A, or GM part number 25524845. This is the brake pedal switch for use with TCC. It has 4 terminals; 2 for the brake lights, and 2 for the TCC. IIRC, the 2 for the TCC are 12v+ until the brake is pressed.

08-17-2009, 09:30 PM	#1
scsindust Registered User Join Date: May 2009 Location: Jessup, MD Posts: 57	Switches on brake pedal I have a brake light switch that has the cruise control cancel in it. Next to that switch is another switch that has what looks to be a vaccuum line attached to it. This vaccuum line hooks into the cruise control module. What is it for, if there are wires for the module going to the brake switch too?? __________________ Jamie Play truck / kid hauler - 1989 V2500 Burb 4x4, 350, 700R4, 4" lift, headers, elec fans, the normal mods. Getting ready for the LS1 swap!!

08-17-2009, 09:37 PM	#2
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	Re: Switches on brake pedal Probably has something to do with disengaging the torque converter clutch (TCC). __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE

08-17-2009, 09:41 PM	#3
scsindust Registered User Join Date: May 2009 Location: Jessup, MD Posts: 57	Re: Switches on brake pedal I guess i should have said that the truck originally came with a TH400, so there was no lockup to start with. __________________ Jamie Play truck / kid hauler - 1989 V2500 Burb 4x4, 350, 700R4, 4" lift, headers, elec fans, the normal mods. Getting ready for the LS1 swap!!

08-19-2009, 11:57 AM	#4
ont_guy_38 Registered User Join Date: Jul 2007 Location: Ontario Canada Posts: 1,006	Re: Switches on brake pedal one of those switches are for the electric kickdown if you have a turbo 400

08-19-2009, 12:02 PM	#5
Driveway Dreams I have car A.D.D. Join Date: Feb 2009 Location: Greeley, Northern Colorado Posts: 4,147	Re: Switches on brake pedal kickdown on the brake pedal? __________________ -Gerald Building vehicles in memory of the first "car guy" I ever knew, my Grandpa. Bob Dunham 1935-2009. Rest in peace. 61 GMC Suburban SOLD The 86 build thread SOLD Are you a Colorado member?Click here.

08-19-2009, 12:12 PM	#6
ont_guy_38 Registered User Join Date: Jul 2007 Location: Ontario Canada Posts: 1,006	Re: Switches on brake pedal LMAO!!!!!!!!...my god hope I dont get the gas and brake mixed up when I,m driving sorry guys a brain fart is the only explanation i got

08-19-2009, 12:34 PM	#7
powerdriver 1958 Kid's Mechanic Join Date: Nov 2006 Location: Kansas City Posts: 8,241	Re: Switches on brake pedal the vac switch is a Vacuum bleed for the cruise control to drop the cruise off,did have a cruise control go haywire and would not shut off but the vac switch on the pedal shut it down when i hit the brakes

08-19-2009, 12:34 PM	#8
Driveway Dreams I have car A.D.D. Join Date: Feb 2009 Location: Greeley, Northern Colorado Posts: 4,147	Re: Switches on brake pedal Brain fart. Crazy cruise control is scary. __________________ -Gerald Building vehicles in memory of the first "car guy" I ever knew, my Grandpa. Bob Dunham 1935-2009. Rest in peace. 61 GMC Suburban SOLD The 86 build thread SOLD Are you a Colorado member?Click here. Last edited by Driveway Dreams; 08-19-2009 at 12:36 PM.

08-19-2009, 09:08 PM	#9
scsindust Registered User Join Date: May 2009 Location: Jessup, MD Posts: 57	Re: Switches on brake pedal Ok, the vacuum line goes to the CC, so then what do the gray & gray/black wires go to on the top of the brake switch? I tested these leads, and they are normally closed, so do these got to the CC too? I would love to disconnect the gray wires and use the switch for the TCC lockup release. __________________ Jamie Play truck / kid hauler - 1989 V2500 Burb 4x4, 350, 700R4, 4" lift, headers, elec fans, the normal mods. Getting ready for the LS1 swap!!

08-19-2009, 10:55 PM	#10
powerdriver 1958 Kid's Mechanic Join Date: Nov 2006 Location: Kansas City Posts: 8,241	Re: Switches on brake pedal yeah wires are CC

08-20-2009, 11:58 AM	#11
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	Re: Switches on brake pedal Can't you just tap into them to use the same leads for the TCC? __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE

08-20-2009, 03:09 PM	#12
scsindust Registered User Join Date: May 2009 Location: Jessup, MD Posts: 57	Re: Switches on brake pedal That's what i wanted to do, but there isn't 12v going to the switch when the CC is off, so I'd have to get rid of the CC to use the switch which I think I am going to do. I only use CC on long trips, so oh well, bye CC. __________________ Jamie Play truck / kid hauler - 1989 V2500 Burb 4x4, 350, 700R4, 4" lift, headers, elec fans, the normal mods. Getting ready for the LS1 swap!!

08-20-2009, 03:39 PM	#13
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	Re: Switches on brake pedal My 85 has two switches, and came equipped from the OEM with a lock-up TH350C and cruise. You need ACDelco part number D850A, or GM part number 25524845. This is the brake pedal switch for use with TCC. It has 4 terminals; 2 for the brake lights, and 2 for the TCC. IIRC, the 2 for the TCC are 12v+ until the brake is pressed. Attached Images __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE Last edited by glock35ipsc; 08-20-2009 at 03:40 PM.



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