VSS/DRAC Question

[rpellicer]

Hi,
I'm considering making mods to the DRAC as some of the posts in the forums suggested. My problem is, there seems to be some conflicting info as to whether my vehicle uses a 2 or 40 pulse VSS. It's a 91 Blazer w/ 350TBI/4L60/NP241. Does anyone know for sure, or is there anything I can check to be certain? Thanks.

 

[Russell]

Alright, I am not 100% sure here... But, If I had to guess, I'd say that the truck came with a 4 pulse VSS, then used a DRAC to convert to whatever signal the different systems needed, starting when they switched to an electronic speedometer.

http://www.chevythunder.com/fuel%20injection%20elect.%20pg%20B.htm

There is some VSS info on this page, just scroll down a bit. Shows pictures of the different types of VSS, so you can visually confirm it.

 

[dyeager535]

drac

 

[rpellicer]

Thanks for the clarification. What threw me off was an article published by JTRthat stated that all TBIs through '91 used the 2 pulse.