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VSS wire or cruise control

laketex

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On my '87 with original auto tranny but swapped in manual tranny, there's a plug and 3 wires going into the back of my speedo on the cluster. What is this? My guess is VSS or cruise control. My truck has been throwing the VSS code so I replaced the cable and that didn't work. This weekend, I pulled the dash off to replace the speedo and found these wires. I'm pretty sure my '79 didn't have these. So what are they? /forums/images/graemlins/crazy.gif
 

HarryH3

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Those wires are attached to an opto-electric detector. It shines an LED into the speedo housing, where a small reflective piece rotates in direct correlation to speed. The reflections of light are then detected and converted into digital pulses (VSS Signal) that are then fed to the ECM and cruise control module.
 

laketex

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Ok that reply sounds just enough like BS that i'm not sure if i'm in the lounge or not. Are you kidding me? So I need those wires? Crap, now i've got to solder them back up. So if i put this cluster back in and the speedo/vss still doesn't work, what is the next thing to look at? /forums/images/graemlins/1zhelp.gif
 

HarryH3

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That's really the way it works. /forums/images/graemlins/eek.gif /forums/images/graemlins/thumb.gif

Did you swap out the instrument panel? Why did you cut the wires? /forums/images/graemlins/blush.gif
 

laketex

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yeah, but now i'm back to my original inst panel with a new speedo inside, and will be installing tommorrow.

I cut the wires cause i thought it was a cruise control and I was impatient...my '79 didn't have that!!!...i'll get them back together tommorrow! /forums/images/graemlins/peace.gif
 

dyeager535

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That'll teach you to mess with stuff before you understand it. /forums/images/graemlins/smile.gif
 

84_Chevy_K10

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Can anyone tell me what color the wire is that will provide my computer with a VSS input when I go TBI on my stock '84 cluster?

We talked about this in the past but came to no conclusion.
 

Hossbaby50

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Same here. I tried to find out what wire in the cruise control harness was the VSS wire and nobody knew. I would like to know, and I would also like to know if it is the right pulse count for TPI (MAF). Thanks

Harley
 

dyeager535

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First off, check out www.jagsthatrun.com

Their VSS chapter is online, you can read up on it there. I would almost bet they have the year breakdown for VSS signals. TPI used the same VSS setup until '91 or so, perhaps later, but I know my '88 TPI and the truck VSS are the same.

A10 I think is the VSS wire on the ECM plug.

You guys are talking about the single wire that comes out of the buffer for the ECM, right? If you get the "right" buffer, there will be a seperate plug for the ECM VSS signal. I can take a pic right now probably of mine, or you can wait a few days and remind me.
 

Hossbaby50

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My truck started off life with a carb (85) but I was told that the cruise control ran off VSS of some sort. I tried to find out about it but nobody seemed to know. I didn't really have an ECM from the factory but supposedly VSS is somewhere on my truck due to the 700R4 and the cruise control.

I already bought the Painless VSS buffer for my truck but have yet to install it. I just haven't gotten around to it.

Harley
 

laketex

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[ QUOTE ]
That'll teach you to mess with stuff before you understand it. /forums/images/graemlins/smile.gif

[/ QUOTE ]

Doubt that. I'm the KING of screwing with stuff before I understand it... /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rolleyes.gif
 

dyeager535

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Cruise box is pretty much right above the gas pedal. Black plastic IIRC, just a bit smaller than the ECM. Working on the VSS buffer pics.
 

dyeager535

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VSS buffer 1

VSS Buffer 2

OK, according to my 1988 Camaro Manual, pin 8 on that connector goes to both VSS and cruise. (if present) Brown wire, goes to the IP connector.

Pin 9 (center obviously) is ground. Blk/Wht in my manual.

Pin 10 is 10amp fused hot in run, bulb test, or start. Pnk/Blk.

If you don't know, almost ALL GM connnectors or the components they connect to are numbered, which corresponds to the number in the manual. It's pitch black outside so I couldn't check that.

I know for a fact the colors changed for certain vehicles/years, and that the connector on mine uses factory wires for some year. Pretty sure I spliced in the color wires that match the manual, closer to the fuse panel, so I could better ID them if need be. I also know the buffer itself changed, you can see on mine that it has another extra pin, some used ECM and cruise "feeds" on seperate wires.

A10 is shown as the ECM pin for VSS in both TBI and TPI for '88 Camaro's, probably almost universal for all GM vehicles that vintage.

And yes, I need to edit those for size, but I was in a bit of a hurry. TPI pics Puts you at the beginning of my "TPI" album, which will eventually have captions for all of the pictures.
 

84_Chevy_K10

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Oops, I think I hacked that crap out already. I'll have to check.

Might have to take my input from behind the speedo.
 

dyeager535

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They are LT/LS1's...same fans, but the LS(? can never remember which I have) has those rubber baffles to improve flow-through at speed.
 

laketex

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yup...it's confirmed. I cut the VSS. Hopefully crimp connectors are sufficient to reattach.
 

frankin5

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harley
in 85 vss comes from the moduel dorian has pictured. pink with black stripe #139 is Ing 1 fused 20 amp. black #150 is ground. yellow #400 goes to pin a on module at brake bracket. brown #449 goes to ecm on those equipped with full computer control motors. 700r4 does not rely on vss in 85. /forums/images/graemlins/k5.gif
 

dyeager535

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As you can see even GM could't keep the fuse size or wire colors straight, so it really depends on you how you will wire it up.

I just wired mine up like an '88 Camaro, because thats the system I have and the manual I have.

What John is talking about for the buffer is the 4 wire setup, as opposed to the 3 wires (cruise and ecm being spliced together) that the Camaro manual calls for.

John, what *terminal* is the ECM feed on? I'm guessing its the "empty" one in my pictures, which might mean I have to rewire. No clue if the ouput for VSS or cruise is different from the buffer, I haven't looked in the manual, but I have a feeling it doesn't tell you if they are the same.
 
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