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Vehicle speed signal to ecu; Auto-> manual conversion
Topic Started: Apr 29 2015, 06:36 PM (1,270 Views)
M4tthewd
Matt

I just finished swapping in a manual transmission into my car, everything physically works, but because the ecu is from a auto, it believes I'm not moving at all because it's not getting a signal from the VSS anymore.

My question, is it possible to use the VSS in the cluster to give the ecu a proper reading?

I've tried wiring the VSS from the cluster up to the ecu but it isn't working. Is it even possible?
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Highwayman
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I suspect you will need an ECU from the car the 5 speed came out of. I believe the automatic uses both the tranny speed sensor and the vss in the instrument cluster. The 5 speed only uses the speed sensor in the back of the speedometer. Sorry, Im not much help here just theorizing.
Edited by Highwayman, Apr 29 2015, 08:28 PM.
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David95237


What do you mean It wont go? Does the motor rev up? Does it go in to gear and not move when the clutch is released?
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Stubby79
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IDK about these little guys, but other GM vehicles won't activate the EGR (and maybe even timing advance) without a VSS signal to tell them the vehicle is moving.

Are you getting a code for it? OBD2?

If someone chimes in with how it works, maybe we can figure a work around for ya...
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Stubby79
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According to this, http://metroxfi.com/wp-content/uploads/2008/12/suzuki_swift_1996.pdf , the automatic VSS is a violet wire and the manual VSS is yellow with a green stripe. Which have you connected the instrument cluster VSS to?

There's also wires/inputs for telling the ECU that you're in gear or in neutral, etc. Do you have a signal telling it you're in drive?
Edited by Stubby79, Apr 29 2015, 09:03 PM.
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M4tthewd
Matt

The car drive perfectly fine, it's when engage the clutch, (which we be letting off the throttle) that it stays at the rpm I was previously at for 1 second and then drops.

I've wired the VSS in the cluster up to the tranny one, but I didn't tell the ecu it was in gear I think. All I did was jump the black/orange and black/red so the ecu thought it was in park so I could start it, and then removed the jumper and this made no difference. Is there another way to tell the ecu it's not in park/neutral?
Does anyone have any theories for the *pause* at rpm, and then the drop? It's kind of messing up shifting. And I think it's cause the alternator belt to slip, because I'm changing gears while it's at roughly 1500rpm instead of like 800. Any help would be VERY much appreciated!
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Stubby79
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Green with blue stripe wire at the trans range switch connector should be the wire that tells it it's in drive.

The ecm might be holding the throttle open intentionally, since it's supposed to be hooked up to an automatic. If fiddling with things doesn't fix it, you'll have to get a manual trans ecu to get rid of it. It should fix any and all drivability issues, I'd think.
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M4tthewd
Matt

Stubby79
Apr 29 2015, 09:31 PM
Green with blue stripe wire at the trans range switch connector should be the wire that tells it it's in drive.

The ecm might be holding the throttle open intentionally, since it's supposed to be hooked up to an automatic. If fiddling with things doesn't fix it, you'll have to get a manual trans ecu to get rid of it. It should fix any and all drivability issues, I'd think.
Unfortunately if I switch the wire harness, I'll have to do an engine swap. Because my 2000 1.3 is FI and I'm TBI. But I didn't know about the in drive wire, do you know if it's 12v or ground by chance? I'll try it out tomorrow! It's already dark here in manitoba. Lol times like this make me dream about a garage.
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Stubby79
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According to the wiring diagram, the trans range switch applies +12v to whichever lead it is set to. Fused 15A, switched. Which should already be that way, if you use the +12v lead at the trans range switch connector. (you could attach the trans range switch to test if it makes a difference, rather than jumping or perma-wiring it together)

And I wasn't suggesting you use the ECU from your donor car, I was suggesting you get an ECU that's equivalent to your own, just for a manual trans, from a junkyard or wherever. I'd think it would be plug and play if its the same year and engine.
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M4tthewd
Matt

The yellow wire is the 12v to the transmission. The green/red stripe is the Drive signal to the ecu. I've hooked it yup and there's no change for idle speed or vehicle speed signal. I've disabled the isc for now, and it's cured my weird idle speed! But the vehicle isn't getting a speed signal, so even though it thinks it's in drive, the isc is still working because there's no vehicle speed registered. So for now it's perfectly driveable, but my scan guage doesn't work :( guess I'll have to calculate mpg the old fashion way lol.

As for the ecu swap, I was lucky enough to find a manual car, I'll have to do a lot of looking to find a ecu for a 1.3 TBI manual. But if I'm lucky I'll find one eventually!
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M4tthewd
Matt

Got a breakthrough, as I mentioned before with the wiring, I've made an extension from the VSS in the engine bay up to the speedo, which now is working. But reading roughly 1/10 of the speed. Could be a bad speedo or the wiring isn't transferring the pluses properly.
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Stubby79
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M4tthewd
Apr 30 2015, 09:54 AM
Got a breakthrough, as I mentioned before with the wiring, I've made an extension from the VSS in the engine bay up to the speedo, which now is working. But reading roughly 1/10 of the speed. Could be a bad speedo or the wiring isn't transferring the pluses properly.
it's probably because the VSS pulses per mile from the hall effect sensor in the transmission are many times higher than the simple 4k pulses per mile (or whatever it is) of the reed switch in the speedo. I assume you're channeling the pulses from the speedo back through to the automatic's VSS line.

GM cars, starting in the 90s at least, operate at 24000 pulses per mile, 6x that of the speedo on these cars. I would assume similar of our automatic transmissions. Assuming you're checking your speed via the OBD2 connection, this is why there is a difference.

Has it made a difference to the behavior of the engine?
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M4tthewd
Matt

Stubby79
May 1 2015, 04:54 AM
M4tthewd
Apr 30 2015, 09:54 AM
Got a breakthrough, as I mentioned before with the wiring, I've made an extension from the VSS in the engine bay up to the speedo, which now is working. But reading roughly 1/10 of the speed. Could be a bad speedo or the wiring isn't transferring the pluses properly.
it's probably because the VSS pulses per mile from the hall effect sensor in the transmission are many times higher than the simple 4k pulses per mile (or whatever it is) of the reed switch in the speedo. I assume you're channeling the pulses from the speedo back through to the automatic's VSS line.

GM cars, starting in the 90s at least, operate at 24000 pulses per mile, 6x that of the speedo on these cars. I would assume similar of our automatic transmissions. Assuming you're checking your speed via the OBD2 connection, this is why there is a difference.

Has it made a difference to the behavior of the engine?
Well I assumed it was because I'm sending a signal through the wrong channel, which I guess I am, so it's not working properly. Where a with a manual ecu, the pluses in the speedo would be calculated properly. And I disconnected the ISC, that cured everything actually. Even idling without the isc is pretty smooth. Not sure how I'll handle -40c winters tho, may have to install a relay and a switch for the isc, but that's not that hard. Even in the auto, with the isc, it would idle stupid, and sound like crap. Now it purrs lol
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Metromightymouse
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Powdercoat Wizard

M4tthewd
May 1 2015, 10:04 AM
Stubby79
May 1 2015, 04:54 AM
M4tthewd
Apr 30 2015, 09:54 AM
Got a breakthrough, as I mentioned before with the wiring, I've made an extension from the VSS in the engine bay up to the speedo, which now is working. But reading roughly 1/10 of the speed. Could be a bad speedo or the wiring isn't transferring the pluses properly.
it's probably because the VSS pulses per mile from the hall effect sensor in the transmission are many times higher than the simple 4k pulses per mile (or whatever it is) of the reed switch in the speedo. I assume you're channeling the pulses from the speedo back through to the automatic's VSS line.

GM cars, starting in the 90s at least, operate at 24000 pulses per mile, 6x that of the speedo on these cars. I would assume similar of our automatic transmissions. Assuming you're checking your speed via the OBD2 connection, this is why there is a difference.

Has it made a difference to the behavior of the engine?
Well I assumed it was because I'm sending a signal through the wrong channel, which I guess I am, so it's not working properly. Where a with a manual ecu, the pluses in the speedo would be calculated properly. And I disconnected the ISC, that cured everything actually. Even idling without the isc is pretty smooth. Not sure how I'll handle -40c winters tho, may have to install a relay and a switch for the isc, but that's not that hard. Even in the auto, with the isc, it would idle stupid, and sound like crap. Now it purrs lol
When my ISC was jacked up I installed a 2 position switch and a momentary button on the dash. Switch up and bump the button for choke in the morning and switch down and bump the button when warmed up. Just 2 wires connected directly to the motor in the ISC and I used battery voltage and it never failed. It was also useful as a cruise control when rolling down the freeway. Oh, and it was great for confusing techs at oil change and smog check places. I'd be sitting in the waiting area and all of a sudden I'd hear the unmistakable sound of a 3 cylinder engine racing at high RPMs and shortly thereafter a sheepish tech would come in and say they couldn't get the engine to return to idle. I'd have to go out and throw the switch and reset it to the proper idle speed. Never understood the need to push the little unlabeled red button. Happened several times.
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M4tthewd
Matt

Metromightymouse
May 1 2015, 01:04 PM
M4tthewd
May 1 2015, 10:04 AM
Stubby79
May 1 2015, 04:54 AM
M4tthewd
Apr 30 2015, 09:54 AM
Got a breakthrough, as I mentioned before with the wiring, I've made an extension from the VSS in the engine bay up to the speedo, which now is working. But reading roughly 1/10 of the speed. Could be a bad speedo or the wiring isn't transferring the pluses properly.
it's probably because the VSS pulses per mile from the hall effect sensor in the transmission are many times higher than the simple 4k pulses per mile (or whatever it is) of the reed switch in the speedo. I assume you're channeling the pulses from the speedo back through to the automatic's VSS line.

GM cars, starting in the 90s at least, operate at 24000 pulses per mile, 6x that of the speedo on these cars. I would assume similar of our automatic transmissions. Assuming you're checking your speed via the OBD2 connection, this is why there is a difference.

Has it made a difference to the behavior of the engine?
Well I assumed it was because I'm sending a signal through the wrong channel, which I guess I am, so it's not working properly. Where a with a manual ecu, the pluses in the speedo would be calculated properly. And I disconnected the ISC, that cured everything actually. Even idling without the isc is pretty smooth. Not sure how I'll handle -40c winters tho, may have to install a relay and a switch for the isc, but that's not that hard. Even in the auto, with the isc, it would idle stupid, and sound like crap. Now it purrs lol
When my ISC was jacked up I installed a 2 position switch and a momentary button on the dash. Switch up and bump the button for choke in the morning and switch down and bump the button when warmed up. Just 2 wires connected directly to the motor in the ISC and I used battery voltage and it never failed. It was also useful as a cruise control when rolling down the freeway. Oh, and it was great for confusing techs at oil change and smog check places. I'd be sitting in the waiting area and all of a sudden I'd hear the unmistakable sound of a 3 cylinder engine racing at high RPMs and shortly thereafter a sheepish tech would come in and say they couldn't get the engine to return to idle. I'd have to go out and throw the switch and reset it to the proper idle speed. Never understood the need to push the little unlabeled red button. Happened several times.
Using the isc as a cruise control is a brilliant idea.... I may in fact do that! I don't actually know what the wiring is for it, or how it works but I definitely will figure something out!
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