Tapping into a VSS signal?
Tapping into a VSS signal? I was just curious if anyone has tapped into an existing VSS signal?
I have a 32 ppr signal on my trans that is used for ABS. I was curious if it would be a viable signal to tap into for the VSS for the ecu? Does it affect the signal when splitting it that it would be a problem? I wouldn't think so but stranger things have caused problems.
The ecu is expecting a 40 ppr signal and that the ecu can be changed for whatever sensor. I have a 4 ppr sensor that I can tie into my speedo cable but I have heard that cruise will not function with that low of a pulse count. Has anyone had any experience with this?
I have been able to find very little info about this so any insight would be helpful.
I have a 32 ppr signal on my trans that is used for ABS. I was curious if it would be a viable signal to tap into for the VSS for the ecu? Does it affect the signal when splitting it that it would be a problem? I wouldn't think so but stranger things have caused problems.
The ecu is expecting a 40 ppr signal and that the ecu can be changed for whatever sensor. I have a 4 ppr sensor that I can tie into my speedo cable but I have heard that cruise will not function with that low of a pulse count. Has anyone had any experience with this?
I have been able to find very little info about this so any insight would be helpful.
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
I have the E38 ECM and the 6L80 transmission. I am tapping into the the VSS signal that runs from the tranmission to the ECM and wiring that into my speedometer. My car is not running so I don't know for sure if it will work but some one else did the same thing and I think it worked in their car. As I understand it you cannot use the one for the ABS, at least on my car.
Tapping into the vss signal between the vss and trans may lower the signal amplitude to the pcm and cause shifting problems. I suggest using the vss outuo pin and having the os modified for correct. output.
This is a manual trans that has a vss on the tail shaft. I am trying to get a vss signal to the PCM that it will be happy with. I have an add on 4 pulse per revolution vss that Ivan put on the speedometer cable. I have heard that 4 ppr is not enough resolution for the ECM to be happy with or for it to operate cruise control properly.
I had heard that the ECM could be changed to expect a different pulse per revolution but was unsure if 32 ppr would be good enough. Guess I need to keep looking. Thanks.
I had heard that the ECM could be changed to expect a different pulse per revolution but was unsure if 32 ppr would be good enough. Guess I need to keep looking. Thanks.
On The Tree
Joined: Jul 2011
Posts: 186
Likes: 3
I'd gamble that 32ppr would work. If not there are solutions to get around it.
I ran a GM DRAC in parallel with the TOSS on a 4l80E (E38/T42) and it worked fine. Is it the correct way? No. Did it work with no side effect? Yes.
I ran a GM DRAC in parallel with the TOSS on a 4l80E (E38/T42) and it worked fine. Is it the correct way? No. Did it work with no side effect? Yes.
GM uses 17 or 40 tooth reluctors, so 32 will be fine.
Difficult to say on the effect of tapping into the signal. I do know there is a threshold voltage needed by the ecu. I found that out when I added a VSS for cruise control. I was able to increase voltage by decreasing the VSS reluctor gap.
And you are correct, the speedo inline VSS does not put out enough pulses for smooth dbw cruse control function.
Difficult to say on the effect of tapping into the signal. I do know there is a threshold voltage needed by the ecu. I found that out when I added a VSS for cruise control. I was able to increase voltage by decreasing the VSS reluctor gap.
And you are correct, the speedo inline VSS does not put out enough pulses for smooth dbw cruse control function.
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Verdad Gallardo GM uses 17 or 40 tooth reluctors, so 32 will be fine.
Difficult to say on the effect of tapping into the signal. I do know there is a threshold voltage needed by the ecu. I found that out when I added a VSS for cruise control. I was able to increase voltage by decreasing the VSS reluctor gap.
And you are correct, the speedo inline VSS does not put out enough pulses for smooth dbw cruse control function.
Difficult to say on the effect of tapping into the signal. I do know there is a threshold voltage needed by the ecu. I found that out when I added a VSS for cruise control. I was able to increase voltage by decreasing the VSS reluctor gap.
And you are correct, the speedo inline VSS does not put out enough pulses for smooth dbw cruse control function.
I would like to just use the VSS on the trans tailshaft as it would be cleaner and easier then the add on unit to the speedo cable.
Thanks for your input.
