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Unusual VSS problem?

Old Mar 26, 2010 | 06:40 AM
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Default Unusual VSS problem?

I transplanted an 02 LQ9 (DBW, w/TAC module) with a Richmomd 6 speed manual trans (no VSS) into my 68 vette. I told the tuner I would not be using VSS. He tells me he only disabled VSS from sending a code, in case I had issues and needed to add a VSS later.
I had stalling issues, so I added a Dakota Digital VSS (8K pulse). Stalling issues cured, good...right? Btw, I'm not using the VSS for a speedo, I'm running a cable speedo.
So I'm looking to add cruise control now...sould be easy with the TAC DBW, but my VSS on a scanner is reading 0 mph at all times.
What am I missing, could the VSS pulse reading cure my stalling and still not read a speed?
BTW, I only have the capability of reading basic parameters.
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Old Mar 26, 2010 | 09:54 AM
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PCM is looking for a 40k pulse, and the cruise will be looking for a 4k pulse from the speedo
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Old Mar 26, 2010 | 10:08 AM
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Thanks for the response. I know the non-DBW cruise control use a pcm generated signal (4k?), is that what you're referring to?
I've been told the DBW setup operates directly from the VSS.
So the big question, will cruise control work as it is, or will I need to reprogram the computer or change the VSS?

Last edited by garys 68; Mar 26, 2010 at 11:16 AM.
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Old Mar 26, 2010 | 03:15 PM
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My guess is would prolly have to change the vss.

I'm not sure if reprogramming the pcm to see a different input signal is an option. be cool if it was though! LOL
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Old Mar 28, 2010 | 07:11 AM
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I "corrected" the DC signal from my original jeep transfer case to the AC signal needed by the GM PCM using a converter from Dakota Digital. That allowed the PCM to see a speed close to the actual vehicle speed which is good for tuning. Also, you can reprogram the pulses in the PCM itself, see HPTuners for that. But you may still need to covert the signal. I had issues with the engine not handling conditions right until I got a close to approximate speed into the PCM. That fixed a lot of issues for my setup.
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Old Mar 28, 2010 | 07:37 AM
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Yep, got some info from a few others here. I'll be looking to program the computer closer to the Dakota 8k pukse. Looks like the pcm is seeing a much lower speed, like 2-3 mph when I'm going 60 mph. But that's apparently enough to cure the stalling issue.
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