1986 Carb to 1993 TBI with VSS Issues !!!

**mh86** · 07-25-2016

Converted vehicle: 1986 Holiday Rambler Imperial 33'
Mark IV 454 4bbl/TH400
The current VSS(signal generator) on speedo cable at trans is (59D-02392-1 / 8ppr).

Donor vehicle: 1993 C3500 HD
Gen V 454 TBI/5 speed

Currently using ECM 1228747 ARPA that was pulled from the '93.
Also have an AKWA and ANRS available. These might make a difference with the 454 and TH400 ???

TBI conversion went smooth and vehicle seems to operate normal after 30 miles of road tests. (loop status functions seem normal with no codes set)

I'm using the 1993 OEM cruise control module for this conversion and not sure what type of pulse signal it requires ? Also what the ECM requires ?
I don't think the current VSS/pulse generator(59D-02392-1 / 8ppr) will send the correct signal to the DRAC and then on to the 1993 cruise control module and the 1228747 ECM.

Below is a list of pulse generators shown at http://www.jagsthatrun.com/Pages/Spe...eedometer.html and I need help choosing the correct one for my application. According to the year models shown it seems like #3 should be the choice, but I just want to be sure because they are rather expensive, so any advice would be most helpful!

1. The two-pulse (2000 pulses per mile) square wave(D.C. current or direct current) used on all TBI engines through 1992, all computer-controlled-carbureted engines, and on 1985–1989 TPI engines.
2. A four-pulse (4000 pulses per mile) sine-wave (A.C. current or alternating current) signal is required by the 1990–1993 TPI, 1992–1993 LT1 engines, and 1990–1993 Camaro 3.1/3.4 V6 engines.
3. A 40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks with automatic transmission, 1994 and newer rear drive cars (Camaro, Corvette, and Caprice) with the automatic transmission.

Attachment 10825 Attachment 10826 Attachment 10827 Attachment 10828

**fastacton** · 08-01-2016

I've been wanting to do some more testing on this stuff, but haven't had a chance lately. I seem to recall the 4 pulse from JTR not working with a DRAC/VSSB, so the two pulse might be the better option and that should be what the '8747 ECM is looking for anyway. I wouldn't do the driveshaft sensor since the 2 pulse should do the job. Call JTR before ordering and ensure they have it in stock, I think I waited about a year the last time I ordered a 2 pulse prom them. I'd stick with the ARPA as that is setup for the injectors that you're using.

**lionelhutz** · 08-02-2016

The '8747 would require a 2ppm square wave signal so if you connected the VSS directly you would use that one.

The DRAC uses a 40 pulse as the input so when using a DRAC you want that signal. But, JTR doesn't sell that as a inline sensor. You'd need to add a reluctor ring and a sensor to the driveshaft or come up with some similar way to do it.

**mh86** · 08-03-2016

Thanks for both replies !!

I have already purchased a 40ppr inline speed sensor (same configuration as my original 8ppr) from jagsthatrun.com based on info from different sources. My only concerns are a working cruise control and making sure the ECM receives the correct signal for idle speeds and any other adjustments that are made during the driving process.

Below is attached a diagram of the Drac I will be using. I'm just hoping the combination of the 40ppr vss and this Drac will allow my (93 cruise module and the 8747 to both receive the correct signals for proper operation).

Any advice would be greatly appreciated !!

Attachment 10854