Need PID for 4 Low Signal (6L80)

[BoulderCharles]

I LS swapped my Land Rover Discovery 2 and one of the remaining items is getting the 4Low to work. I have developed a CANbus gateway so I am able to send/receive CAN messages. It?s an E38 ECM from a 2010 Silverado.

Does anyone know the PID and messages to enable / disable 4 Low?

I?ve tried the extended PID 0x2D1 with the first message (byte A) set to either 0x00 (off?) or 0x01 (on?) but that doesn?t seem to work. Anyone know the right PID/messages?

Extra credit if you also know the PID/messages for the Tap Up and Tap Down signals.

Thanks in advance!

[JBMotorsport]

Any joy on the tap up/down??

[verlon]

I LS swapped my Land Rover Discovery 2 and one of the remaining items is getting the 4Low to work. I have developed a CANbus gateway so I am able to send/receive CAN messages. It?s an E38 ECM from a 2010 Silverado.

Does anyone know the PID and messages to enable / disable 4 Low?

I?ve tried the extended PID 0x2D1 with the first message (byte A) set to either 0x00 (off?) or 0x01 (on?) but that doesn?t seem to work. Anyone know the right PID/messages?

Extra credit if you also know the PID/messages for the Tap Up and Tap Down signals.

Thanks in advance!

You have to send 5 byte frame periodically every 100ms with arbitration ID $2D1.

$2D1 - Transfer Case Status
100ms Periodic PTEI3 TCCM
+0.7 - MIL Request
+0.6 - Service 4WD Indication On
+0.5 - 4WD Active
+0.4 - Transfer Case Mode Validity (0=Valid)
+0.3:0.0 - Transfer Case Mode
0 = 2WD
1 = 4WD Hi
2 = 4WD Lo
3 = Active AWD
4 = 4WD Hi
5 = 4WD Lo
6 = 4WD Lo
7 = Neutral
8-15 = Invalid
+1.4:1.3 - ??? 4WD Mode
0 = 2WD
1 = 4WD
2 = Fault?
3 = Invalid
+1.2 - 4WD Low Mode Validity (0=Valid)
+1.1:1.0 - 4WD Low Mode
0 = Inactive
1 = Active
2 = Fault?
3 = Invalid
+2:3 - Diagnostic Trouble Code Caused MIL Request
+4 - ?

[BoulderCharles]

You have to send 5 byte frame periodically every 100ms with arbitration ID $2D1.

$2D1 - Transfer Case Status
100ms Periodic PTEI3 TCCM
+0.7 - MIL Request
+0.6 - Service 4WD Indication On
+0.5 - 4WD Active
+0.4 - Transfer Case Mode Validity (0=Valid)
+0.3:0.0 - Transfer Case Mode
0 = 2WD
1 = 4WD Hi
2 = 4WD Lo
3 = Active AWD
4 = 4WD Hi
5 = 4WD Lo
6 = 4WD Lo
7 = Neutral
8-15 = Invalid
+1.4:1.3 - ??? 4WD Mode
0 = 2WD
1 = 4WD
2 = Fault?
3 = Invalid
+1.2 - 4WD Low Mode Validity (0=Valid)
+1.1:1.0 - 4WD Low Mode
0 = Inactive
1 = Active
2 = Fault?
3 = Invalid
+2:3 - Diagnostic Trouble Code Caused MIL Request
+4 - ?

Thanks! Can you clarify the "+0.7" rows? Are those additional bytes that need to be sent with the PID $2D1? Or do I just need to send the same signal with <=100ms frequency?

[BoulderCharles]

Any joy on the tap up/down??

I ended up using the hardwired approach as I couldn't find the PIDs and my PSI harness had the TU/TD wiring included in the trans harness. It works fine and there are a few threads talking through the process.

[TheMechanic]

You have to send 5 byte frame periodically every 100ms with arbitration ID $2D1.

$2D1 - Transfer Case Status
100ms Periodic PTEI3 TCCM
+0.7 - MIL Request
+0.6 - Service 4WD Indication On
+0.5 - 4WD Active
+0.4 - Transfer Case Mode Validity (0=Valid)
+0.3:0.0 - Transfer Case Mode
0 = 2WD
1 = 4WD Hi
2 = 4WD Lo
3 = Active AWD
4 = 4WD Hi
5 = 4WD Lo
6 = 4WD Lo
7 = Neutral
8-15 = Invalid
+1.4:1.3 - ??? 4WD Mode
0 = 2WD
1 = 4WD
2 = Fault?
3 = Invalid
+1.2 - 4WD Low Mode Validity (0=Valid)
+1.1:1.0 - 4WD Low Mode
0 = Inactive
1 = Active
2 = Fault?
3 = Invalid
+2:3 - Diagnostic Trouble Code Caused MIL Request
+4 - ?

OK so where did you find/learn this, and where does this go to function with the scanner? In a working folder? Some form of software update?

[verlon]

Thanks! Can you clarify the "+0.7" rows? Are those additional bytes that need to be sent with the PID $2D1? Or do I just need to send the same signal with <=100ms frequency?

+0.7 - Byte 0 bit 7
+0.3:0.0 - Byte 0 bits 3..0

[verlon]

OK so where did you find/learn this, and where does this go to function with the scanner? In a working folder? Some form of software update?

Sniffing and reverse engineering, mostly ECM, TCM and BCM.
Scanners does not use normal communication messages, they are requesting PIDs and DIDs (data blocks).

[TheMechanic]

Sniffing and reverse engineering, mostly ECM, TCM and BCM.
Scanners does not use normal communication messages, they are requesting PIDs and DIDs (data blocks).

What hardware/software are you using for this?

[BoulderCharles]

+0.7 - Byte 0 bit 7
+0.3:0.0 - Byte 0 bits 3..0

Ah, thanks. I'm less familiar with breaking down the bits in this way. Do you know the hexadecimal code for Byte0 to signal 4WD on? And does it span across Byte 0 and Byte 1?

Also, any chance you know the various brake signals the ECM wants to see to allow cruise control? I've gathered it needs 3 different brake signals but I'm not certain exactly with Arb ID and Bytes need to be sent.

[verlon]

Ah, thanks. I'm less familiar with breaking down the bits in this way. Do you know the hexadecimal code for Byte0 to signal 4WD on? And does it span across Byte 0 and Byte 1?

Also, any chance you know the various brake signals the ECM wants to see to allow cruise control? I've gathered it needs 3 different brake signals but I'm not certain exactly with Arb ID and Bytes need to be sent.

You can try this:
00 00 00 00 00 - 2WD
21 08 00 00 00 - 4WD Hi
22 09 00 00 00 - 4WD Lo

Brakes and cruise is a bit more complex matter. Those frames ($0F1 - brakes and $1E1 - cruise) have rolling protection counters. It's much easier to use BCM for brakes and cruise.

[verlon]

What hardware/software are you using for this?

MDI with DrewTech J2534 Analysis Tool. IDA for disassembling.

[TheMechanic]

MDI with DrewTech J2534 Analysis Tool. IDA for disassembling.

Going to check that out. I have a GM MDI2 and Techline Connect that has a data bus diag tool but it obviously does not do what yours does.