Hello all, new to the forum. Having problems with my 08 Savana 4.8L. Setting code for lost com with pcm, bcm. Also says start disabled, service throttle. I have been checking grounds and checked the OBDII plug. I get power and grounds at the OBDII plug as well as a good Ohm reading. Was hoping someone would have access to some wiring diagrams as well as can splice and ground splice block locations. Any help would be great. Thanks

 

Always make sure you're starting with a healthy electrical system. Have your battery + alternator tested with a proper load tester. (usually a free courtesy at battery dealers and part stores)

What is the code?
If you are getting Uxxx communication codes from a diagnostic scan, then that's not a problem with the OBD port. That's communication between the modules in the car.
If your tool is saying it's unable to connect to the car, then yeah it might be the port.

I presume this is a message you're seeing on your instrument panel?

reading on what, and how many ohms?

You might be able to find schematics on gmupfitter.com

 

Thank you for your reply.
1) The van has a new battery and the charging system has been checked. 14.54V
2) Code U0100
3) I have checked the OBDII port with a volt/ohm meter. Pin 16=battery voltage. Pin 4&5 show ground. Pins 6 to 14 show 61 ohms.
4) Yes the instrument cluster shows the (start disabled/service throttle).
5) Yes, I enjoy South Main Auto on YouTube.

I will be checking the connector at the throttle body for any broken wires as this seem to be a known issue from what I seen in my hunt. I have been trying to track down grounds to clean and check. Have replaced the ground strap from the frame to the block as the strap did not take much to pull apart. (Thanks Eric, SMA for that video)
I have found some green meenys at the fuse box under the hood. Whether that is going to go anywhere or not, ?
When I turn the key to the on position I get a flickering check engine light and a clicking sound from the fuse box in the engine bay but can't track the sound to any of the relays. Unless there is also something mounted under the fuse panel. ?
Again, thanks for the reply.

 

Always check your bulletins first.
This might be relevant
https://static.nhtsa.gov/odi/tsbs/20...15080-9999.pdf
Did you try clearing the code and wait and see if it comes back? Could just be a glitch.

That means nothing. That's why I said: have your battery + alternator tested with a proper load tester. (usually a free courtesy at battery dealers and part stores)


Then your port is fine.
Have a read here:
https://www.obd-codes.com/U0100

Make sure the ground is solid. There should be less than 1 ohm between bare body metal and pin 5.


Ignore that for now, it could be a secondary symptom.
Probably nothing will work until you fix U0100
that's suspicious. Try pulling some fuses/relays

 

Battery was tested with an OTC 3150 and showed to be good and full charge.
Have not made it to anything else yet.
Thanks for the replies.

 

those are prone to false readings. Carbon pile are the only testers that can be trusted.