Unable to establish communication

[Doug Rostad]

Depends on what he means by the "Power" not being hooked up. Is this the X1 connector or the X2 connector. I think it will still pass data without the X1 power being connected as long as X2 is connected. If X2 is disconnected, it will need to be jumped. The Resistance test I keep bringing up will answer a lot of these questions.

Tonight I will check the resistance,,,, as the video pertained to. the plugs are all in the EPS just not the large power positive plug.

 

[Gtstorey]

I don't think the modules needs to be "awake" or "powered up" to pass on the data. They only need to be awake for them to send/receive their own data.

The power steering, OBDII port, BCM, and ECU all need to be plugged in and properly grounded for the system to work. The 120Ohm resisters are in the power steering and the ECU.

 

[Doug Rostad]

Ok,,,, soooooooooooo, I hooked the EPS Power wire up to 12 volts then with the key off, I checked resistance.... I have 120.6 Ohms across terminals 6 & 14 Indicating one of the computers has an issue. So I started disconnecting one plug at a time from the BCM . Each plug out , I checked the resistance. still 120.6 Ohms. now after each plug at the ECM. Still 120.6 Ohms. disconnected plug from ECM to engine harness. Still 120.6 Ohms. I completely removed the fuse box the ECM and the BCM. Still 120.6 Ohms. I unplugged the only other wire having to do with the network. the EPS . Of coarse it went to 0 Ohms that is where the data link goes to first.

 

[Ross]

So you are getting 120 ohms from the EPS, and need to get GM high speed LAN (aka Canbus) connectivity thru the BCM to the 120 ohm resistor in the ECM. Then your OBDii port pins 6 & 14 should read 60 ohms.
For my LSJ wiring harness, here is the GM high speed LAN wires.
Your LAP wiring can be found on my build thread index page:
Manuals and diagrams:
manual for your goblin donor. downloadable 7-zip or WinRar

 

[Doug Rostad]

120 Oms to the tan wires in the BCM and 120 Ohms to the brown wires and brown and white wires at the BCM

 

[Gtstorey]

Don’t start in the middle. Start at one end. And we need more information than what you give us in the last post. Draw us a picture or post screen shots of the wiring diagram with PIN numbers were you are taking measurements.

 

[Doug Rostad]

So the tan and white wires with 120 Ohms goes to the 16 pin engine harness not to the PCM

 

[Joebob]

Use this bookmark to go through your wiring plugs to determine where the brake in the data wires is. As soon as you unplug the ECU you will lose that resistor. Start tracing from the OBDII port to the BCM and check for continuity through the pins in the connectors and work your way to the ECU. I found I was getting intermittent disconnects in the pin receptacles in the BCM plug.

V1 - BAR-AIR's build up in Buffalo N.Y.

Yes those are 5 3/4” lenses. Just make sure they are the DOT lenses. Those were advertised as DOT lenses but when they showed up no DOT markings. Took about a month of back and forth with the manufacturer before they sent a set of DOT lenses. Nate’s car is using a set of 5 3/4” headlight shells...

dfkitcar.com

 

[Gtstorey]

From 2009 service manual.
Start with the resistance at bn/wh to bn at the eps connector with it disconnected.

 

[Joebob]

Take a look at this schematic on the data wires. For me with an auto, it goes through the TCM that yours does not. you will go from the BCM to the ECU, but the connectors and pin numbers are there to help find the break.

 

[Doug Rostad]

So the tan and white wires with 120 Ohms goes to the 16 pin engine harness not to the PCM

120 Oms to the tan wires in the BCM and 120 Ohms to the brown wires and brown and white wires at the BCM

Ok what should I be looking for here? Yes the key is on. As soon as the battery is connected, the dash lights come on. Throttle plate does not cycle clutch in turn key BCM has clicking noise. but, no crank. the passkey shows "lockout" I tried to relearn the key, lockout light never turns off after 10 minutes.

Take a look at this schematic on the data wires. For me with an auto, it goes through the TCM that yours does not. you will go from the BCM to the ECU, but the connectors and pin numbers are there to help find the break.

View attachment 45566

I will print this out tomorrow. Thanks

 

[Gtstorey]

You can’t guess or assume wires/connections when diagnosing these problems. Take the time to look it up. Hopefully Ross’s link has connector end views to check PIN numbers to make sure you are on the correct ones.