I just bought an autometer 5" ultra-lite electronic speedo. Will it work with a 97 T56's VSS? If not, what will I need to get it to work?

 

The speedo should have instructions on calibration for the T56. I read in another post about someone doing this.

 

i bought an autometer 3 3/8 elec. speedo and it should be a simple 2 wire hookup. i also read that a buffer box my not be needed as the speedo sends out a buffered signal that you can run to your ecm... haven't tried it yet (car won't be road ready till this weekend... but you should have no probs getting it to work. i know a lot of other guys have similar setups

 

Anyone have a for sure answer on whether the speedo will generate a buffered signal for the ECM? I'm getting ready to buy the parts for my swap and would rather just buy a whole new speedo than an adapter box and cable drive. Thanks, Joe

 

I used the 5" Autometer speedo for my T56 conversion.

It works fine with the stock T56 VSS.

You will need a buffer box to convert the T56 signal for use with the ECM. The speedo doesn't provide an output for the ECM, and if you run the T56 signal directly into the ECM you will have some interesting results, since the signals from a T56 VSS and a 3rd gen VSS are totally different.

 

I found this on autometer's website. http://hp.autometer.com/instruction_...ctions/510.pdf
It shows an output to the PCM on the wiring diagram, and says that it will give a buffered signal. But is this the converted PPM signal or is it just the same signal amplified so that there is no signal loss? Thanks, Joe

 

joe, that's exactly what I'm wondering.
The T56 vss sensor is a 2 wire, so I know which diagram to use; I'm just not so sure it will work.

What's the pulse/per mile signal of a 90-92 TPI? And is it different for auto or T5?
What's the ppm signal of a 97 T56?

 

The 90-92 is 4,000 pulse per mile and is the same for the auto and T-5. The VSS and gears are not the same for the auto and t-5.

The T-56 is 40 pulses per driveshaft revolution, thats just over 100,000 PPM. ( gears and tire size will change the PPM the 40 per driveshaft revolution is fixed.)

The ECM on a 90-92 needs to see 4,000 PPM to run so you will need a buffer box or remachine the tailshaft housing to fit your 90-92 VSS to get the 4,000 PPM signal.

Link for the "how to machine your T-56 for 3rd gen VSS."

https://www.thirdgen.org/techbb2/sho...=jerrywho+attn

I have done this for for others here.

Jerry

 

I'm not using the t5/old style vss UNLESS I absolutely have to. I'd like to avoid the hassle of removing the tailshaft and having it machined. That was one of the deciding factors of going with the fancy autometer speedo. Now it's all a matter of whether I'll have have to use a buffer box or not. I want to make sure that if I wire it up like the AutoMeter instructions say, it will work like it's supposed to and cooperate with the ECM/PROM. Or will I have to take that into account when tuning my PROM?

 

Damn Jerry! I'd rather play dodge 'em on the freeway during rush hour than attempt the modifications in that link you posted!

 

Seriously, listen to what I'm saying. You need a buffer box. This subject has been debated to death on about four other threads. The speedo can't make the 4th gen signal into a 3rd gen signal that the ECM will understand.

I don't post stuff like that for my health!

 

Thanks guys!
What's the name of the buffer box? Who makes it? Is there better ones to use and ones I should avoid?

It will be good to have a working speedo again.
And an accurate tach also.

 

Dakota Digital SGI-5.

 

Thank you!