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Electrical way to "kill" speedometer on cable driven speedo?
Posted: Thu Jan 17, 2013 4:27 pm
by MConte05
Background on why I want to do this: When on a rally stage, pushing 90-100 mph I sometimes briefly look down at the speedometer and freak the fuck out and back off the throttle, or brake early.
What I want to do: Maintain the speedometer on transits and daily driving, but flip a switch to kill the speedometer before a stage start, and flip a switch to turn it back on after the stage is over.
However, I have a cable driven speedometer, and wondering if it is possible to kill it. Or is it directly driven? If its directly driven.... then a little piece of tape and a notecard saying "Don't Lift" will have to do I suppose.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 5:14 pm
by kimokalihi
I doubt there's an easy way to pull that off without interrupting the signal to the ecu and that will mess with your engine in a bad way.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 5:49 pm
by MConte05
I don't recall the engine having issues when the speedo was disconnected in the first place. It seems the older (91) ECU's don't depend on speed as much as the newer cars do.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 6:45 pm
by Someperson
Yeah, cable speedos are direct drive. You can pop it off at the trans and tape over both ends to keep dirt out
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 8:25 pm
by mike-tracy
In contrary, the lack of VSS signal makes a significant impact on how the car drives.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 8:43 pm
by BoostedSubie
what about just putting a piece of tape over the speedo so you don't see your speed, lol.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 9:17 pm
by MConte05
mike-tracy wrote:In contrary, the lack of VSS signal makes a significant impact on how the car drives.
The car had a broken speedo cable for about the first 3 months I owned it. Raced Perryville rally without the speedo and used the rally computer as a speedometer. Never noticed a change in how the car ran, or MPG.
But it looks like tape will have to do. Oh well.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Thu Jan 17, 2013 11:10 pm
by kimokalihi
Well that's odd. I have a 91 and it threw codes for the vss and other things with it disconnected and it was in limp mode the whole time.
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Fri Jan 18, 2013 2:49 pm
by FundamentalyConfused
BoostedSubie wrote:what about just putting a piece of tape over the speedo so you don't see your speed, lol.
I'll agree with this guy. Just take a colored piece of paper and tape it over the speedo and put a smiley face on it so you can happily go fast!
Re: Electrical way to "kill" speedometer on cable driven spe
Posted: Fri Jan 18, 2013 7:19 pm
by Legacy777
As mentioned above, the cable driven speedos are directly driven and can't be interupted.
As for the ECU needing a speed input, yes it does, and can be very tempermental if it doesn't have one. The radiator fan control has speed dependent characteristics, as well other functions in the ECU. Certain ECU's may be more tempermental than others though, JECS vs. Hitachi.