VSS in General
04-10-2014, 08:15 PM
#1
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VSS in General
7730 ECM, 700 R4, believed to be 2-post VSS (2003 Pulses per Mile [PPM} behind a mechanical speedometer (can't see what's there without a lot of trouble)
Have been going through the AUJP $8d VSS code and have some questions. In the process, have read every post on VSS I can find. Lots of info, but nothing consolidated. So here goes initially with some, hopefully, simple questions:
Have been going through the AUJP $8d VSS code and have some questions. In the process, have read every post on VSS I can find. Lots of info, but nothing consolidated. So here goes initially with some, hopefully, simple questions:
- Short of ripping out the dash, how can it be determined what post-type of VSS is installed?
- Is there anything that can be logged to determine same?
- MPH is reported correctly per GPS, speedometer and via TunerPro (all agree), but the code has the PPM constant L8015=0xE6 indicating 4006 PPM. Does that mean I have a 4-pole VSS, or would MPH be reported correctly with a 2-pole VSS with the 0xE6 constant?
- What would be the constant for 2003 PPM (0xE6 / 2 = 0x73)?
04-10-2014, 11:53 PM
#2
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Car: '90 Trans Am-12.45@110.71
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Re: VSS in General
It's an optical sensor behind the speedo.
Put the speedo wire in C6 on the 7730 ECM and change the constant "to not magnetic"
Put the speedo wire in C6 on the 7730 ECM and change the constant "to not magnetic"
04-11-2014, 07:43 AM
#3
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Car: check
Engine: check
Transmission: check
Re: VSS in General
RBob.
04-11-2014, 11:25 AM
#4
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Re: VSS in General
Also, can you shed some light on what the counter L3FE2 is reporting (AUJP $8d)?
Thanks!
04-13-2014, 10:33 PM
#5
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Re: VSS in General
Right, but forgot to mention that L8018 b6 is set indicating magnetic sensor, so the 4k PPM factor 0xE6 is being used and MPH is correctly reported. My confusion is that with a mechanical speedometer, would not the middle, 2-output VSS in the attachment be installed? Prior owner indicated that's the one. And if so, how is it that MPH can be reported correctly with the 4k factor? Just trying to understand the logic.
Also, can you shed some light on what the counter L3FE2 is reporting (AUJP $8d)?
Thanks!
Also, can you shed some light on what the counter L3FE2 is reporting (AUJP $8d)?
Thanks!
04-14-2014, 11:29 AM
#6
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Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
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Re: VSS in General
The VSS input to the ECM can be either magnetic (4 pulse per rev) or optical.
Each has its own scale factor.
The speedometer is operated via an output from the ECM at 2K.
VSS does not directly operate the speedo on the dash.
Jp
The second 2K output from the ECM operates the cruise control (if equipped)
Each has its own scale factor.
The speedometer is operated via an output from the ECM at 2K.
VSS does not directly operate the speedo on the dash.
Jp
The second 2K output from the ECM operates the cruise control (if equipped)
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