Clarification on VSS input for 16197427 swap

[Chewy1576]

Hey all,

I picked up a 16197427 (BJDR) ECM from a 1994 C2500 with a 350/4L80E. Already have new blue and red ECM connectors and KS6 knock sensor. G1 adapter and ZIF socket will cover the chip conversion.

i have been reading through Dave's and Mark's conversion threads and I'm not quite sure what to do with the VSS input. I think the new ECM is looking for a 2k PPM signal on Input F13. Will the existing input on the current 1228747 plug right in, or will I need to find a DRAC/VSSB to work?

I'm assuming that the 1228747 is similar enough to the 1227747 that I can follow the same pin relocations, swap the knock sensor, bypass the ESC Module, and it will work?

[buddrow]

Hey all,

I picked up a 16197427 (BJDR) ECM from a 1994 C2500 with a 350/4L80E. Already have new blue and red ECM connectors and KS6 knock sensor. G1 adapter and ZIF socket will cover the chip conversion.

i have been reading through Dave's and Mark's conversion threads and I'm not quite sure what to do with the VSS input. I think the new ECM is looking for a 2k PPM signal on Input F13. Will the existing input on the current 1228747 plug right in, or will I need to find a DRAC/VSSB to work?

I'm assuming that the 1228747 is similar enough to the 1227747 that I can follow the same pin relocations, swap the knock sensor, bypass the ESC Module, and it will work?

If your truck doesnt have the 88-92ish dash with the "built in DRAC" then yes, you will need to run an external DRAC module and add all the requisite wiring. Someone may correctly so take what I say with a grain of salt.

Buddrow

[Chewy1576]

If your truck doesnt have the 88-92ish dash with the "built in DRAC" then yes, you will need to run an external DRAC module and add all the requisite wiring. Someone may correctly so take what I say with a grain of salt.

Buddrow

My truck has Moonie gauges with the built in DRAC. I have a 7 way DIP switch ready to solder in in place of the resistors as I'm going to be changing from 3.42 to 4.10 gears in the future also.

[myburb]

I am using 6395/7427 OE and you have the option of manipulating gear ratios in the bin in parameter overdrive ratio. I just changed tire size and corrected via the bin.

[Chewy1576]

I am using 6395/7427 OE and you have the option of manipulating gear ratios in the bin in parameter overdrive ratio. I just changed tire size and corrected via the bin.

i was going to use the DIP to correct the speedometer after the gear change. I'm running 285/65/18's also.

[myburb]

When I changed the transmission went back to normal operation and I ran a gps to check the speedo which seemed right on. There is quite a range that you can manipulate. If you take a look at a OE hac you will see the calculations the use. With standard tires and 4:10 gear the number is in the 47 range. With standard tires and 3:73 the number is is the 42 range and with my larger tires and an effective ratio of 3:62 the number is in the 40 range. I am not at home now so just giving recalls.

[dave w]

The 93 - 95 4L80E should have both an Input speed sensor (wired directly to the PCM) and a 40 pulses per driveshaft revolution VSS (wired to the DRAC). I favor using the DRAC with either a 4L60E or 4L80E.

dave w

[Chewy1576]

The 93 - 95 4L80E should have both an Input speed sensor (wired directly to the PCM) and a 40 pulses per driveshaft revolution VSS (wired to the DRAC). I favor using the DRAC with either a 4L60E or 4L80E.

dave w

Will I still need both signals with a manual transmission? Currently running an NV4500.

[dave w]

Will I still need both signals with a manual transmission? Currently running an NV4500.

No Input Speed Sensor wiring needed when using the 16197427 with a NV4500.
The 2000 Pulses per Mile VSS can be wired directly to the 16197427 when using the NV4500.

dave w

[Chewy1576]

That is exactly what I was looking for. Thank you Dave!

[Chewy1576]

One more question...

I have a KS6 knock sensor ready to go in the block. Will jumper out the ESC module work or should I wire the ESC output to the Knock Sensor input at the PCM?

[dave w]

The 16197427 has "one" wire from the computer going straight to the Knock Sensor.

The ESC module has four wires, Ground wire, Ignition wire, a wire from knock sensor, and a wire to computer. You can solder splice the wire from the knock sensor to the wire that goes to the computer, which electrically makes "one" wire from computer to the knock sensor. Terminate the unused ECS Ground and Ignition wires.

dave w

[Chewy1576]

Awesome. That is the route I was going to go but wanted reassurance it was correct. The electrical drawings show dark blue from the sensor to the ESC Module, then yellow and black or black from the ESC to the ECM on terminal B7. I will terminate those two together to create a single path from the sensor to the ECM, then clean up the remaining wires. Thanks again Dave!