LS1MCSS

iTrader: (18)

They may not answer, considering that the original post is almost 2 years old. Autometer speedometers are programable so they don't have to have a 4000 pulse per mile output, even though that is what the gm pcm puts out. The pulse per mile signal depends on the teeth on the reluctor ring and rear end gears. If the settings in the pcm programming are correct, it will calculate the correct output.

busta9876

iTrader: (3)

This is all programmable in the PCM. In stock programming, the speed pulse input is calibrated to tire size, axle ratio, and 40 pulse per drive shaft revolution. This works out to 80,000 to 110,000 pulse per mile INPUT depending on tires/axle.

With programming the PCM can be setup to read a lower pulse input, with the dakota sensor, you end up with a value around 3.0 to 3.5 pulse per drive shaft revolution to come up with 8000 pulse/mile.

The VSS OUTPUT signal is 4000 pulse/mile, stock GM speedo output. This can be set to a different value if needed, I've used 2000 pulse for some older GM stuff, and 8000 pulse for Chrysler factory speedometers.

Crazyjpr66

had a 5.3 swapped into my 2002 TJ. Still running my NV 3550 and NP231. All so running both computers. Everything runs good and gages all work BUT when I'm coming off of a high speed ( like off the highway) to a stop the Jeep will die on me. I can punch it before it dies and it will not die.
I am being told that I need to install a reluctor ring to fix this. Yes the VSS is hooked up. The engine shows no speed on the computer. Talked with Dakota Digital and they said the SGI-5E would not fix my problem because SGI-5E only make a speedometer work.
Any ideas on this??? If I have to go to a reluctor then how well would it hold up. It's a Jeep that will see water crossings, mud ect. Would this reluctor work going through a mud hole or creek crossing? Thanks for any advice you can give me.

gagliano7

Sounds more like a tuning issue.

Suncc49

There is a kit out there that attaches to the rear pinion I believe and measures that way....

Crazyjpr66

what I'm finding out is Jeep transmission and transfer case puts out a DC pulse and the GM only reads AC so working on changing the pulse to AC.

Floader

iTrader: (32)

If you get crafty with HP tuners you can tune out most/all of the stalling issues. It took me a while (im not that good with HP) but I got a CJ5 with a 5.3/SM465 combo to run fine with no speed sensor hooked up to the computer.

AHenry014

Bump due to having the same exact setup; same engine, trans, and Tcase. My tune does not have an issue with stalling, but i have a light for P0507, which is for "idle control speed too high", or something along those lines. After doing research, it appears as though this code can be caused from having no VSS hooked up, which i do not. It makes sense since the PCM with no speed input things its at 0 mph and that i am just revving sitting still. Where the PCM gets confused is on decel when the TPS is at 0% and its calling for the programmed idle speed, but my decel RPM is higher than that, triggering the check engine light. I also have popping in the exhaust on decel due to it not cutting fuel on decel as well, which is quite annoying. In talking with my tuner, we already set the PPR to 3 when i told him i would be retaining the Jeep VSS, which sounds like a step in the right direction. In talking with Dakota Digital, they state that i need SGI-5E, which should be here in the next couple days. I am hoping to get it installed this weekend, but wanted to make sure i have all my ducks in a row.

I am aware the Jeep VSS is 8000 PPM. Setting the PPR in the GM PCM to 3 results in a similar 8000 PPM (correct?). Now where the issue lies is the difference between the Jeeps square wave DC VSS signal and the AC Sin wave input that the GM PCM is looking for. I need the SGI-5E module to covert this signal. Which "application" should i be following on their setup sheet? I think #2 is correct, but not certain. That should give me direction on how this is to be wired, then just need to figure out setup.

AHenry014

Got it figured out. "Application 2" in the Dakota instructions for SGI-5E. "VSS High" into GM PCM goes to "Out 1" on DD module. Jeep VSS (white/orange on my 2002 TJ) to "VSS input". 3 PPR set in tune.