ABS Light, Speedometer Jumping, Transmission Won't Detent

So I'm having some fun issues with my S10 Blazer right now.

1992 S10 Blazer 4x4 4.3L TBI, 4-speed auto (not electronic)

ABS Codes- 41, 42, 46, 51, 52, 65, 67, 68
The speedometer is jumping around sporadically.
Gas mileage has dropped astoundingly. ½ tank has gotten me 80 miles!!!! Poorest MPG ever!!

Also, may be related, the tranny has shifted properly for awhile. Slips from 4th to 3rd when letting off the gas at highway speed, and won't detent shift 4th to 3rd even with the gas completely floored. I had the tranny rebuilt in November and had the detent cable replaced a couple of weeks ago. I'm going to make sure it was adjusted correctly today by using the shop manual method: shift the cable back and ratchet forward with throttle or gas pedal.

As far as the ABS and speedometer go, I'm going to test what I can with the vehicle speed sensor (VSS) and the DRAC module today. With my WinALDL scan tool, I found it is definitely not a speedometer issue because the speed coming from the computer is fluctuating as well.

There is a test in the shop manual to do, but are there any other tests for the VSS or DRAC module? Reason here is because I replaced the VSS after the tranny rebuild in November. So either the DRAC module is acting up or something in the transfer case is screwed.

Your thoughts?

Here are my testing results:

Tranny in gear (OD) with rear wheels raised and moving at idle speed- scan tool reads 0mph.

As per shop manual testing chart-
DMM on 20vdc between pins 8 & 11 on VSS buffer (DRAC) module- .07vdc, no change with speed.

Pin 8 (ground) to pin 12 (VSS input- out B)- .05vdc
Pin 8 (ground) to pin 7 (VSS input- out A)- 0vdc

Old VSS- 1277 ohms, New VSS- 1217 ohms

Tested continuity on CKT 822 and 821, both good with .004 ohms resistance between them.

With this testing and the flowchart, it leads to a bad DRAC module. With that, I would like to test the components of the DRAC: resistors, chips, etc. Are there any known issues with certain components in these modules?

If I can just replace a sensor or a chip, etc, I will just have to do some soldering.

Thanks.

If anyone is interested in the solution to this, it was wiring. There is a jumper wire that extends the VSS lines for the transfer case (obviously not needed when 4x4 is not present), and those lines were messed up. Fixed them up and no more VSS or DRAC issues. When in doubt, check the wiring!!

If anyone is interested in the solution to this, it was wiring. There is a jumper wire that extends the VSS lines for the transfer case (obviously not needed when 4x4 is not present), and those lines were messed up. Fixed them up and no more VSS or DRAC issues. When in doubt, check the wiring!!

with no response on this being a 1992 , hard from here to say whats the issue [vehiclecondition ]..........My guess is the wiring loom materal wore/broke up. then the wire insulation chewed into the transfercase body shorting out your vehicles signal .

make sure you get new loom to protect all these wires then the vacuum lines as well....from chaffing....