Help! Can't connect to obd2

STROKETHISF350

STROKETHISF350

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I have an 06 dodge that's been under the knife for 5 months and I just got everything out back together to where I could start it and can't get my v2 or my cts2 to connect to the ecm. The truck does start and all the guages work but I can't connect to the ecm with anything. I don't know where to begin, also I have a bench harness that I was able to connect to the ecm with to change the vin but can't connect in the truck


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Does obd2 have power? So your scan tool will power up but it just doesn't connect to the ECM? What about other modules? If it's not powering up check the fuse for the cig lighter
 
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Get a break out box and check all the pins in the obd2 to see if they have the correct voltage. Or if one of the pins is dead
 
Not sure what a break out box is but am should I see any voltage for the can wires on the obd port ?


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Assuming this is the only way to check it ? Just curious but do the can wires go from the ecm to the tipm, gauge cluster etc ?


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Yes, the CAN wires do go from ECM to TIPM, to all other modules.
If you look around on here, I believe I have the pinout for the OBDII port posted somewhere.
I believe I posted it in one of the EFILive sub forums.

Mark.
 
Pinout scheme for OBDII:

Cavity Function

4 Ground
5 Ground
6 Can +
14 Can -
16 Fused Battery +

I'm not @ home, so I can't tell you wire colors, I do know that the CAN +/- wires both are white with either a blue or green stripe from the ECM.

Mark.
 
Mark Nixon said:
Yes, the CAN wires do go from ECM to TIPM, to all other modules.
If you look around on here, I believe I have the pinout for the OBDII port posted somewhere.
I believe I posted it in one of the EFILive sub forums.

Mark.
Click to expand...


Thanks for the reply, I got on all data at a friends shop and was trying to find schematics so I could trace the can wires from the ecm to where ever they go next not sure if that's the tipm or some other module but couldn't hardly find what I was looking for, mostly being a pin out of the big connector that goes on the firewall from the engine harness. I'm wondering if I could have a bad tipm etc since I already know for sure the problem isn't with the ecm itself


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Have we checked for power at the OBDII? I wouldnt go jumping to any conclusion until you've checked that.
 
Yes as stated above it does have power and ground at the obd connector, my cts2 and v2 both turn on when plugged in but will not communicate, I wish it was as simple as a cigar fuse like typically it is


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If you have power, yet no data exchange, then it's a communication problem.
Like many politicians. :D

In the harness to the OBDII port, there are 2 white wires, one with a green and the other a blue stripe, though at the OBDII port there can SOMETIMES be one with a brown stripe, depending on where it was removed from (gasser).
These are the CAN wires.

Sometimes the OBII ports have a different color to them (again a brown tracer), then you need to go by pin numbers, not color.
Just be sure they aren't flip flopped and that they go to the correct pins.

The ecm will NOT communicate if these 2 wires are reversed, though it typically won't HURT anything if they are accidentally connected backwards.

Mark.
 
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Mark Nixon said:
If you have power, yet no data exchange, then it's a communication problem.
Like many politicians. :D

In the harness to the OBDII port, there are 2 white wires, one with a green and the other a blue stripe, though at the OBDII port there can SOMETIMES be one with a brown stripe, depending on where it was removed from (gasser).
These are the CAN wires.

Sometimes the OBII ports have a different color to them (again a brown tracer), then you need to go by pin numbers, not color.
Just be sure they aren't flip flopped and that they go to the correct pins.

The ecm will NOT communicate if these 2 wires are reversed, though it typically won't HURT anything if they are accidentally connected backwards.

Mark.
Click to expand...


I checked the resistance from the c1 connector pin 4&5 for the can hi&lo at the ecm to the large plug on the fire wall and they have good continuity so I'm assuming the problem lies after that but I can't figure out which wires on the tipm are the can wires or even if that's where the can signal goes first, give me a few and I'll check voltages at the can wires on the obd port


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The CAN wires are solid wired, no fuses, just connections where the plugs come together.
On a Cummins truck, these are white with a blue tracer and white with a green tracer.

Be sure you check on the plugs, such as the big c-130 plug and be sure the pin is actually engaged, sometimes the locks fail and they can push the connector pins away, losing contact.

One thing, as I mentioned, the CAN wires are not fused or switched, so if the connection fails, all that happens is no communication somewhere.

I'd about bank on it being between the ECM and the OBDII port.

Don't forget to check the sandwiched connector behind the bulkhead grommet, too!

Mark.
 
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