6395/7427 without drac

[myburb]

There is a flag in the 6395/7427 OE/31 that is "output speed not from drac". Does that mean you can connect vss directly to pcm and do ratio conversions in the appropriate area in the bin? I realize there might not be any speedo output but the unit I am thinking of has gps speedo so not a problem.

[dave w]

I've directly connected a 2000 Pulses Per Mile VSS (square wave) directly to pin F13 and set the "output speed not from drac" without issue.

dave w

[JeepsAndGuns]

I've directly connected a 2000 Pulses Per Mile VSS (square wave) directly to pin F13 and set the "output speed not from drac" without issue.

dave w

That's how I have mine set up. No issues.

[myburb]

I might be understanding the vss incorrectly. The output ring is 40 tooth and the shaft roughly turns 2300 per mile which makes roughly 95000 pulses per mile. Wondering where your 2000 pulses per mile comes from. I thought that was the output of the drac. On a side note when you get a calculator and start dividing those 95000ish divided by the numbers in the overdrive ratio and you start to see a possible correlation.

[dave w]

I think I see some confusion.

You are correct, the DRAC outputs 2000 pulses per mile to the computer.

The DRAC can be eliminated, (for example when a vehicle does not have a 40 tooth output ring), by using an aftermarket 2000 pulses per mile VSS directly to the computer. When you eliminate the DRAC, its a good plan to set "output speed not from DRAC".

I was thinking you want to eliminate the DRAC?

Getting back to your original question: setting "output speed not from DRAC" will enable a VSS signal filter to ensure a clean square wave VSS input. Setting "output speed not from DRAC" Does Not enable a ratio conversion.

dave w

[myburb]

Got it now. Thanks