LBZ bench harness questions

[boothybunch]

Finally getting round to building my harness and doing dsp5 on my spare ecm.

Just a little confused with the ECM pin out.

On the efi live tutorial, it states you have to use 2 pins on the large connector as well as 6 on the small connector BUT on diesel place it shows (thanks to biodiesel66)

C2 -- OBDII
P1 -- P16 pos. Batt. Voltage
P2 -- P 5 and P 4 GND
P9 -- P 2 Serial Data Class 2
P21 -- ignition switch on
P44 -- P14 – GMLan High Speed Serial Data
P57 -- P 6 + GMLan High Speed Serial Data

There is no mention of any connection of the large connection

Also planning on putting a plug onto the harness for TCM access if i decide to have that tuned as well as I understand you got to have an ECM plugged in. I assume I just couple up to the gmlan connections.

Just after confirmation so i can proceed.

[boothybunch]

will no-one put me out my misery???

[GMPX]

It is probably not necessary to connect the +Batt (12V Unswitched) and +Ign (12V Switched) on the large connector. Some ECM's require a constant 12V feed for when you are changing a VIN etc, I don't think the Bosch ECM does.
The Allison TCM will work by itself but you need to put a 120 Ohm load across the CAN bus (CAN Low ----120 Resistor --- CAN High), the ECM would normally provide the CAN bus loading.

[THEFERMANATOR]

It is probably not necessary to connect the +Batt (12V Unswitched) and +Ign (12V Switched) on the large connector. Some ECM's require a constant 12V feed for when you are changing a VIN etc, I don't think the Bosch ECM does.
The Allison TCM will work by itself but you need to put a 120 Ohm load across the CAN bus (CAN Low ----120 Resistor --- CAN High), the ECM would normally provide the CAN bus loading.

I thought it was the glow plug module that put the load on the CAN BUS? I know I read that if you remove the GPCM, you have to install a resistor across the bus to make it work.

[GMPX]

ECM works fine on the bench by itself so it must have a CAN load in it.

[DURAtotheMAX]

ECM has CAN termination in it.

Not sure about GPCM.

TCM may or may not have CAN termination in it depending how its wired.

Remember, on 06-07 8.1 trucks, the TCM was the only module on GMLAN. I think if you loop the wires back to the other GMLAN terminals on the TCM, it creates the 120 ohm termination/resistance on the hi/low circuits.... or something like that. It (TCM) obviously works as standalone in 8.1 trucks, and as far as I know, there is no external 120ohm termination resistor used on 06-07 8.1 trucks.

Ben

[GMC-2002-Dmax]

MY EFI Connections A40/A50 Bench Harness has a CAN Termination pre wired

[boothybunch]

well It's been confirmed I only need the 58 pin Connector ( C2)

Was planning on buying the EFI connection harness, but by time I had purchased the harnesses and power supply, it's $300 + shipping over to uk which was hilariously high (for some reason) and then on top of that i would have to pay at least 10% import duty and then 20% value added tax on top. It's tooo much.

already have the allison connector (from the uk dealers, 5 mins away from me) so all i needed was the C2 and pins.

If i get my hands on a spare TCM, i will try the 120 ohm resistor and come back to you.

I also think I got a stroke of good look. Was looking at having to buy another licence for my V2 (second hand) but by the looks of it, The spare ecm I have (from seller of v2) has been linked to this V2 so I shouldn't need one to have a play.

[DURAtotheMAX]

Interesting...so you've done partial flashing, full flashing, VIN change, and locking with no C1 connector hooked up?

Also.... in your original post....you say Pin 1 on the C2 connector is "battery constant voltage"....on all the wiring diagrams I can find, Pin 1 is "ignition switched voltage"???

[boothybunch]

Interesting...so you've done partial flashing, full flashing, VIN change, and locking with no C1 connector hooked up?

Also.... in your original post....you say Pin 1 on the C2 connector is "battery constant voltage"....on all the wiring diagrams I can find, Pin 1 is "ignition switched voltage"???

I spoke to mark at huskstorf diesel who asked the same question on dieselplace a few years ago and he said "When I do a bench flash of the ECM I only use one connector. It has worked great for many years. I am not sure what EFI is referring to. "