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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: mcintyrederek on December 30, 2013, 05:40:06 pm

Title: Identify this device
Post by: mcintyrederek on December 30, 2013, 05:40:06 pm

Hi,
Please see attached pic.  What is this thing that hooks to the instrument panel and what does it do?

Title: Re: Identify this device
Post by: mcintyrederek on December 30, 2013, 05:41:20 pm

Sorry, forgot to post the info.  1986 C10 Silverado that came originally with a 4.3, TH400, cruise, delay wiper, and air.

Title: Re: Identify this device
Post by: roboticjunky on December 30, 2013, 06:08:21 pm

VSS (vehicle speed sensor) buffer. It uses the pulses from the back off the speedometer and buffers the signal to the ECM (computer) for what speed you are going.

Title: Re: Identify this device
Post by: mcintyrederek on December 30, 2013, 07:05:51 pm

Thanks.  So, I am guessing it probably has a capacitor and a few other components in it to filter out the pulses and maybe send a voltage to the ECM.

This is obviously doing nothing for me, as someone who owned the truck prior took the 4.3 out and stuck a 350 crate motor in it.  Not much wiring was hooked back up except for the bare minimum.  None of the emissions, knock sensor, or anything else..  all those connectors were dangling loose.  I am supposing it had an air pump on it and a cat converter at one time, too. 

So, if I just disconnect this device it shouldn't hurt anything or affect any performance whatsoever?  I am running a Q-jet (without any electrical hook-ups), and the transmission obviously wouldn't feed off the ECM being it's a TH400 and the only electrical hook-up on it is the detent solenoid.

Title: Re: Identify this device
Post by: roboticjunky on December 30, 2013, 07:54:13 pm

Only other thing that vss buffer would be used for would be cruise control, but doubt your truck has it or if it did it's probably not hooked up anymore.

Title: Re: Identify this device
Post by: mcintyrederek on December 30, 2013, 08:38:24 pm

Yep, that's what it was used for.  Cruise.  It did come factory on this particular vehicle.  Some unplugged the wiring harness and cut the vacuum line when they changed the engine.

This truck doesn't look to have an ECM, not that I can see anyway.

Title: Re: Identify this device
Post by: Captkaos on December 31, 2013, 11:47:20 am

It would have an ESC controller behind the glove box unless it was removed.  That would be used for cruise.  It shouldnt hurt leaving it there.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

Title: Re: Identify this device
Post by: mcintyrederek on December 31, 2013, 06:52:15 pm

Okay, yes I see that device behind the glove box and a little to the left.  I didn't know what it was so I didn't bother it.  Since someone threw all the cruise stuff away before I got the truck, I'll just leave it disconnected.