Any OBD experts out there? What is the command to send to obtain data from these sensors? (I have a Scanguage)Front Propshaft Speed Sensor - The transfer case shift control module converts the pulsating AC voltage from the front transfer case speed sensor to front propshaft speed, in RPM to be used for calculations, and to monitor the difference between the front and rear sensor speed. It is also used in the AUTO 4WD mode to determine the amount of slip and the percent of torque to apply to the front axle. The front propshaft speed can be displayed with a scan tool.
Rear Propshaft Speed Sensor - The transfer case shift control module converts the pulsating AC voltage from the rear transfer case speed sensor to a rear propshaft speed, in RPM to be used for calculations. The rear propshaft speed can be displayed with a scan tool.
Vehicle Speed Sensor - One of the 2 speed sensors on the rear output shaft is the vehicle speed sensor (VSS) input to the powertrain control module (PCM). The PCM sends this information to the transfer case shift control module via the Class 2 serial data bus.
reading speed sensors
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Topic author - I have my van tatooed on my cheeks
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reading speed sensors
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Topic author - I have my van tatooed on my cheeks
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Re: reading speed sensors
I just found potential PID's for these sensors:
Transmission Input Speed: Mode $22 PID $1941
Transmission Output Speed: Mode $22 PID $1942
I'll test these soon and post my results.
Transmission Input Speed: Mode $22 PID $1941
Transmission Output Speed: Mode $22 PID $1942
I'll test these soon and post my results.
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Topic author - I have my van tatooed on my cheeks
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Re: reading speed sensors
That's a good website astrozam, but it looks like it's just about trouble codes. This topic is about querying the PCM for vehicle information. They are called Mode 22, enhanced GM, or non-standard parameters. GM charges $50K for access to this kind of proprietary information, and you have to go into a non-disclosure agreement with them. Some people manage to reverse-engineer them though, so a few float around the internet.
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Topic author - I have my van tatooed on my cheeks
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Re: reading speed sensors
I'm going to start posting my findings in this topic:
http://www.astrosafarivans.org/bb2/view ... =10&t=5826
http://www.astrosafarivans.org/bb2/view ... =10&t=5826
Re: reading speed sensors
Hey Timeless!
How's your research going on VSS? Mine is bugging the heck out
of me for some generated RF interference.
Craig 'Lumpy' Lemke
www.n0eq.com
How's your research going on VSS? Mine is bugging the heck out
of me for some generated RF interference.
Craig 'Lumpy' Lemke
www.n0eq.com
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Topic author - I have my van tatooed on my cheeks
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Re: reading speed sensors
Hi Lumpy.Lumpy wrote:Hey Timeless!
How's your research going on VSS? Mine is bugging the heck out
of me for some generated RF interference.
Craig 'Lumpy' Lemke
http://www.n0eq.com
There are protocols for the transmission input and output speeds, and they are supported on my van. I haven't been able to decipher the data yet though. My reference material is very limited, so it's like stabbing in the dark.
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Topic author - I have my van tatooed on my cheeks
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Re: reading speed sensors
One reference tool I'm using is this Wiki page: http://en.wikipedia.org/wiki/OBD-II_PIDs
For the PID's which I've captured with my Scanguage 2 (SG), I'm getting 2 byte responses instead 1, and 3 byte responses where I should get 2 (such as 0x10 MAF). It's possible that the ECU appends some kind of control byte or CRC to the data, but which position? Also, I thought the SG handles error correction itself.
For the PID's which I've captured with my Scanguage 2 (SG), I'm getting 2 byte responses instead 1, and 3 byte responses where I should get 2 (such as 0x10 MAF). It's possible that the ECU appends some kind of control byte or CRC to the data, but which position? Also, I thought the SG handles error correction itself.