anyone know what these switches/units r for? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SYCOTIK · 11-09-2011, 10:47 PM

The trucks an '87. They're mounted to the side of the brake pedal bracket under the column. Its has cruise control which I believe the black box has something to do with since part of that harness plugs into it, but I could b wrong? But what about the switch next to it? What that for?

Also, while I'm at it, this lil box was under the dash too and has a few other wires that plug into the other end. It looks like it has 2 tiny lights inside that black piece at the end. Any ideas?

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**old Rusty C10** · 11-09-2011, 11:25 PM

that green thing with the wire .. i have one of them and that is bolted with a small quarter inch bolt into the back of my speedometer at the wire end... that is definately cruise control id be surprised if the silver thing is not a relay of some kind and the other is prolly cruise too

rs72z · 11-09-2011, 11:25 PM

Quote:

Originally Posted by SYCOTIK

The trucks an '87. They're mounted to the side of the brake pedal bracket under the column. Its has cruise control which I believe the black box has something to do with since part of that harness plugs into it, but I could b wrong? But what about the switch next to it? What that for?

Also, while I'm at it, this lil box was under the dash too and has a few other wires that plug into the other end. It looks like it has 2 tiny lights inside that black piece at the end. Any ideas?

Posted via Mobile Device

I'll take a stab. Black box is for cruise. relay is for power locks, I think could be windows and the green box i believe hooks to the speedometer for vss for the ecm. If i'm not right please correct me

tucsonjwt · 11-09-2011, 11:27 PM

I can confirm that the black box is the cruise control module. I don't know about the others.

rs72z · 11-09-2011, 11:34 PM

Just pulled the power window and locks harness out of a 84 suburban this weekend to use with my suburban doors, that eneded up not working with my 88-91 doors. So i know the relay is either windows or lock relay. I'm about 99 percent sure the green box is the vss signal.

SYCOTIK · 11-10-2011, 01:42 AM

Thanks for the responses guys. Appriciate it.
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Evil Trailblazer SS · 11-10-2011, 09:58 AM

The Green Box is the Speed Buffer while is what the cruise control system on the newer trucks use to sense the vehicle speed (VSS).
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BLE 'BURBAN · 11-10-2011, 11:09 AM

In order left to right - cruise control module, power lock relay and vehicle speed sensor for cruise control.

SYCOTIK · 11-10-2011, 12:58 PM

Ok thanks. So here's my next question. I bought a new chrome column that will not have cruise control. Can I ditch the black and green boxes or r they still needed even without cruise?
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rs72z · 11-10-2011, 02:30 PM

Is it fuelinjected? I believe that the ecm needs it work properly.
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Desert1957 · 11-12-2011, 12:29 PM

Quote:

Originally Posted by rs72z

Is it fuelinjected? I believe that the ecm needs it work properly.
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Without the "VSS" vehicle speed sensor , the ECM will run in open loop. Which means it takes no input from any other sensors, engine runs on fix preset parameters. Also the "Check Engine" light will stay on full time.

Desert

SYCOTIK · 11-10-2011, 04:46 PM

Yeah its TBI
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406 Q-ship · 11-10-2011, 05:47 PM

Green box is the Vehicle Speed Sensor (VSS) for the emission/fuel injection system. The black box is the cruise control module. The large relay is for the power locks.

SYCOTIK · 11-10-2011, 07:23 PM

Since I have shaved door handles I can ditch that lock relay right? Or is relay for locks AND windows? Could i get rid of the black cruisecontrol module too since no longer will have cruise control? What about the green vss module? Still need it?
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11-09-2011, 10:47 PM	#1
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	anyone know what these switches/units r for? The trucks an '87. They're mounted to the side of the brake pedal bracket under the column. Its has cruise control which I believe the black box has something to do with since part of that harness plugs into it, but I could b wrong? But what about the switch next to it? What that for? Also, while I'm at it, this lil box was under the dash too and has a few other wires that plug into the other end. It looks like it has 2 tiny lights inside that black piece at the end. Any ideas? Posted via Mobile Device

11-09-2011, 11:25 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	Re: anyone know what these switches/units r for? that green thing with the wire .. i have one of them and that is bolted with a small quarter inch bolt into the back of my speedometer at the wire end... that is definately cruise control id be surprised if the silver thing is not a relay of some kind and the other is prolly cruise too __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-09-2011, 11:27 PM	#4
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,189	Re: anyone know what these switches/units r for? I can confirm that the black box is the cruise control module. I don't know about the others.

11-09-2011, 11:34 PM	#5
rs72z Registered User Join Date: Oct 2011 Location: Emory TX Posts: 900	Re: anyone know what these switches/units r for? Just pulled the power window and locks harness out of a 84 suburban this weekend to use with my suburban doors, that eneded up not working with my 88-91 doors. So i know the relay is either windows or lock relay. I'm about 99 percent sure the green box is the vss signal.

11-10-2011, 01:42 AM	#6
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	Re: anyone know what these switches/units r for? Thanks for the responses guys. Appriciate it. Posted via Mobile Device

11-10-2011, 09:58 AM	#7
Evil Trailblazer SS Big Gulps Huh? Whelp... Join Date: Apr 2010 Location: Reno, NV Posts: 410	Re: anyone know what these switches/units r for? The Green Box is the Speed Buffer while is what the cruise control system on the newer trucks use to sense the vehicle speed (VSS). Posted via Mobile Device __________________ "The Ghost II" - 1987 V30 CC, 14-BFF (2nd Design Heavy Ribbed HD) SRW Conversion, 454/4L80E/205, 6" Springs, 35" Toyo MT's on 17" Classic II's, Full Audio System, Lot of Other Goodies!

11-10-2011, 11:09 AM	#8
BLE 'BURBAN In the Forgotten far North. Join Date: Jul 2007 Location: Anchorage, Alaska Posts: 2,627	Re: anyone know what these switches/units r for? In order left to right - cruise control module, power lock relay and vehicle speed sensor for cruise control. __________________ 1987 R3500 CREW CAB DUALLY (BIG RED)Acquired 06/12/2015 1990 chevy suburban V2500 5.7L My cluster Mods-Nov 2007 overhead console Stereo install Round 2 Aug 2009 Heated/turn signal mirror upgrade

11-10-2011, 12:58 PM	#9
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	Re: anyone know what these switches/units r for? Ok thanks. So here's my next question. I bought a new chrome column that will not have cruise control. Can I ditch the black and green boxes or r they still needed even without cruise? Posted via Mobile Device

11-10-2011, 02:30 PM	#10
rs72z Registered User Join Date: Oct 2011 Location: Emory TX Posts: 900	Re: anyone know what these switches/units r for? Is it fuelinjected? I believe that the ecm needs it work properly. Posted via Mobile Device

11-10-2011, 04:46 PM	#12
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	Re: anyone know what these switches/units r for? Yeah its TBI Posted via Mobile Device

11-10-2011, 05:47 PM	#13
406 Q-ship Registered User Join Date: Oct 2010 Location: Largo Florida Posts: 632	Re: anyone know what these switches/units r for? Green box is the Vehicle Speed Sensor (VSS) for the emission/fuel injection system. The black box is the cruise control module. The large relay is for the power locks. __________________ Lifes journey is not to arrive at the gate well preserved, it is to slide in sideways all used up and wore out yelling.....God what'a ride! Where patience fails, force prevails Stapp's Ironical Paradox "The universal aptitude for ineptitude makes any human accomplishment an incredible miracle."

11-10-2011, 07:23 PM	#14
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	Re: anyone know what these switches/units r for? Since I have shaved door handles I can ditch that lock relay right? Or is relay for locks AND windows? Could i get rid of the black cruisecontrol module too since no longer will have cruise control? What about the green vss module? Still need it? Posted via Mobile Device

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