NefMoto > Technical > Tuning > How is VSS read by the ECU?
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Author Topic: How is VSS read by the ECU?  (Read 32384 times)
AmIdYfReAk
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« on: April 26, 2011, 10:15:01 PM »
I'm trying to get this correct in my head.... is the VSS done by the cluster and transported via Canbus for the ME7.5.5 Ecus?

I'm in the middle of a swap, And would like to take advantage of Launch/no lift/etc but a Speed input is required.

All of the documentation that i have all show it being plugged into the Automatic Transmission Sub-ECU, And in all other cases into the Gauge cluster ( directly? ).
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240sxpooter
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« Reply #1 on: April 26, 2011, 11:10:01 PM »
Quote from: AmIdYfReAk on April 26, 2011, 10:15:01 PM
I'm trying to get this correct in my head.... is the VSS done by the cluster and transported via Canbus for the ME7.5.5 Ecus?

I'm in the middle of a swap, And would like to take advantage of Launch/no lift/etc but a Speed input is required.

All of the documentation that i have all show it being plugged into the Automatic Transmission Sub-ECU, And in all other cases into the Gauge cluster ( directly? ).


 This depends on the car and if the Vss is from transmission => cluster=>ECU or if the Vss is from wheel speed sensors => abs => cluster=>ECU.
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AmIdYfReAk
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« Reply #2 on: April 27, 2011, 06:09:22 AM »
so for those of us that are doin a swap and refusing to use the cluster, were screwed? =D
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240sxpooter
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« Reply #3 on: April 27, 2011, 06:47:14 AM »
Quote from: AmIdYfReAk on April 27, 2011, 06:09:22 AM
so for those of us that are doin a swap and refusing to use the cluster, were screwed? =D



Kinda. unless you start making a CANBUS VSS converter!
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NOTORIOUS VR
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« Reply #4 on: April 27, 2011, 08:26:14 AM »
I'm lost... what ECU are you using for the swap?  ME7?

But you're not willing to use the stock cluster?
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Tony@NefMoto
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« Reply #5 on: April 27, 2011, 10:54:33 AM »
I'm 90% sure that the ME7 ECU does not have any connections for vehicle speed or wheel speed sensors.

If you want those signals, then the simplest thing to do would be to use something like an Arduino board with a CAN bus shield. Then you would need to figure out which messages contain the speed data, and then output that on a digital or analog pin on the Arduino board.
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AmIdYfReAk
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« Reply #6 on: April 27, 2011, 12:08:36 PM »
Quote from: Tony@NefMoto on April 27, 2011, 10:54:33 AM
I'm 90% sure that the ME7 ECU does not have any connections for vehicle speed or wheel speed sensors.

If you want those signals, then the simplest thing to do would be to use something like an Arduino board with a CAN bus shield. Then you would need to figure out which messages contain the speed data, and then output that on a digital or analog pin on the Arduino board.

if your 90% sure, then I'm 99.999% sure, out of the vast diagrams and etc that I have it shows the signal going to the automatic ecu or the cluster for any manual setups...

I'll check into that kinda stuff and see how it turns out, but it's sounding like a project for further down the line. =D

motors been waiting 3 years to get between the rails.

Quote from: NOTORIOUS VR on April 27, 2011, 08:26:14 AM
I'm lost... what ECU are you using for the swap?  ME7?

But you're not willing to use the stock cluster?



me 7.5.5, late 1.8t awp.

and yep, you got it correct...
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Tony@NefMoto
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« Reply #7 on: April 27, 2011, 12:19:35 PM »
I would say 100% sure, but the users on this forum always seem to prove me wrong.  Grin
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Giannis
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« Reply #8 on: April 27, 2011, 12:38:21 PM »
Tony and how about cruise control? How the ecu can correct the desired speed if it doesn't have awreness of the vehicle speed? I think that it can read it somehow. Mayby by carculating rpm vs gear in gearbox.
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Tony@NefMoto
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« Reply #9 on: April 27, 2011, 12:40:55 PM »
The ECU determines what gear you are in based on vehicle speed and RPM.

The ECU is told the vehicle speed over the CAN bus. I can double check this later in the assembly code if anyone wants to know for sure.
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AmIdYfReAk
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« Reply #10 on: April 27, 2011, 10:36:21 PM »
Quote from: Tony@NefMoto on April 27, 2011, 12:19:35 PM
I would say 100% sure, but the users on this forum always seem to prove me wrong.  Grin

Thats a good sign, we've got some smarts around here. Smiley
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orienz
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« Reply #11 on: April 30, 2011, 04:25:57 PM »
I don't think ECU really cares what gear you are in. It tries to maintain given speed with what it has...
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Tony@NefMoto
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« Reply #12 on: May 02, 2011, 02:13:13 PM »
Quote from: orienz on April 30, 2011, 04:25:57 PM
I don't think ECU really cares what gear you are in. It tries to maintain given speed with what it has...

There are maps in the ME7 ECU for gear specific boost limits, etc, and that is what it uses the current gear for.
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gremlin
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« Reply #13 on: May 02, 2011, 05:27:35 PM »
Quote from: Tony@NefMoto on April 27, 2011, 12:40:55 PM
The ECU is told the vehicle speed over the CAN bus. I can double check this later in the assembly code if anyone wants to know for sure.

Don't waste time to check it.  Smiley  You are right 1000%
ECU recieve VSS info through СAN-bus from cluster.
Just catch CAN-message with ID=320h
Also ECU return velocity info back to СAN as a part CCS data packet.
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Tony@NefMoto
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« Reply #14 on: May 03, 2011, 12:03:13 PM »
Quote from: gremlin on May 02, 2011, 05:27:35 PM
Don't waste time to check it.  Smiley  You are right 1000%
ECU recieve VSS info through СAN-bus from cluster.
Just catch CAN-message with ID=320h
Also ECU return velocity info back to СAN as a part CCS data packet.

I like all of your posts gremlin. Please continue making them.  Grin
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