VSS, TAC Module

**midrange** · 02-04-2012

I am trying to diagnose my cruise control issue. I pulled a code today which is P0608 - VSS Output.

Alll this is linked with the PCM and the TAC. The TAC sends out pulses to let the car know its speed in lamens terms. Does that mean this is what controls my speedo?
Is there seperate feed for the speedo from the TAC for the cruise?

I ask because everything seems to work for the TAC as far as radio turns up automatically at higher speeds, and speedo works just fine. Just my cruise doesn't work. Its like the car doesn't know what speed to kep it at when set.

I'm not sure if what I asked makes any sense. I was thinking there may be 2 speed control switches to have seperate control between speedo, and TAC, but it seems our car has one..

I hear of people changing out wires on the TAC, are they known to go bad?

**matt5112** · 02-04-2012

TAC moves the throttle blade.

VSS is vehicle speed which drives the speedo.

**midrange** · 02-04-2012

so why would I be getting a VSS DTC if its working fine?

I think i'm going to pull apart my TAC tomorrow. I'll start there and see what condition the board is in. It sits on top of the motor where heat builds up and cancause dry solder points.
I'm going that step first as another issue people say is starting issues.. Ihave had a few times when i go to start it, it chugs fora second, then stalls, and when i try again, it fires up. Sometimes takes 3 times.. But its been said replacing the TAC can fix that, so perhaps this may be a starting point.

I have no clue, all I know is it drives me nuts when something doesn't work on my car.

**midrange** · 02-04-2012

DOes anyone have a wire diagram for the speedometer

**BillBoost37** · 02-06-2012

Originally Posted by midrange

DOes anyone have a wire diagram for the speedometer

If you'd share with us what you drive, it would probably make things much easier. Personally, I'd look up the code at Gearchatter.com before pulling apart the potentially wrong thing.

**midrange** · 02-06-2012

DAMN IT! I keep forgetting that.. SOrry, I finally edited my Sig. The Code is actually the VSS Ouput. I'm not pulling apart the speedo. I just need to see the wire diagram to find it its ran seperately from the VSS output on the PCM thatgoes to the TAC.. which is the dark greenwire.. This is all to check to see why my cruise is not working.

**BillBoost37** · 02-06-2012

Now, please go look it up at Gearchatter and read the operation/diagnostic aids so you understand what is going on.

You don't want to have this be like a 406 EGR Insufficient Flow where someone replaces the EGR valve that is perfectly good. Code names can be misleading. You need to understand what/how to diagnose and fix it properly.

**midrange** · 02-06-2012

Originally Posted by midrange

DAMN IT! I keep forgetting that.. SOrry, I finally edited my Sig. The Code is actually the VSS Ouput. I'm not pulling apart the speedo. I just need to see the wire diagram to find it its ran seperately from the VSS output on the PCM thatgoes to the TAC.. which is the dark greenwire.. This is all to check to see why my cruise is not working.

here is where i told you why i needed the wire diagram. i'm looking at specific wires.. the guy who will be fixing it asked me to find the cruise diagram and the speedo diagram... that way he is able to diagnose something. I have the cruise diagram, not i just need to see the speedo diagram. not trying to sound like a dick.. i appreciate your help and i understand what your saing about codes.. I just need that diagram as a process of illimination.