Sporadic loss of power to gauge cluster and climate control

[Xanderbilt]

My 2009 G37x is experiencing an electrical gremlin. Occasionally upon startup the climate control won't turn on & the gauges won't work. The slip, traction and brake warning lights also light up. Sometimes it resolves on its own while driving, other times it takes days before it resets and everything works again. Does anyone have any ideas?

[cfauvel]

Yes I DO have an idea, and you are NOT going to like it.

It is an issue with your high speed CAN bus, the network of your car.

You have one of these issues somewhere on your network.
CAN HIGH shorted to ground
CAN LOW shorted to ground
CAN HIGH shorted to pos
CAN LOW shorted to pos
Both wires shorted together
or resistive short on either wire to ground, POS or to themselves
or intermittent OPEN on these wires.

Now for the crappiness.....WHERE?!?!

I am new to learning about the CAN bus and other bus system in the car, BUT from what I've learned dealing with my G35 and 350z is that there are few components to keep in mind and where they are.

The buses in the car ALL have to get combined into a GATEWAY, and it is NOT the ECM. On our cars the GATEWAY is the Unified Control Module (90% sure of what I am saying) and that lives on the instrument cluster. Surprisingly enough the wiring diagram shows the UCM being connected to the A/C control module and also surprisingly doesn't control JUST the A/C (I don't recall ALL that it controls).


I've read here that replacing the A/C control module fixes stuff on the front of the instrument cluster, like lights, fuel gauge level, but am highly suspect of that. But THAT being said a used A/C control module is cheap on ebay and junk yards so MAYBE worth taking a look.


Do you go through car washes regularly? My G35 does and have narrowed down my issue (about 90% sure) to being some short in or around the transmission wire loom for the TCM , as I have similar issues and worse as you about an hour after going through the car wash. My car is in the shop :-) Hopefully the guy is good at finding CAN bus issues.

try to keep tabs as to WHEN it happens. Such as only on first startup of the day after sitting for several hours, every time you startup.

Maybe look up where all the modules are located and disconnect /reconnect each one that is easily accessed. In doing so you might get lucky and be just a loose connection between a pin and its connector, or you might SEE a bad wire.

I don't know the colors for the CAN bus wires...BUT they will be 2 wires that are twisted together. I believe ONLY network wires (CAN, LIN, etc) are twisted pair.

[VStar650CL]

Yes I DO have an idea, and you are NOT going to like it.

It is an issue with your high speed CAN bus, the network of your car.

You have one of these issues somewhere on your network.
CAN HIGH shorted to ground
CAN LOW shorted to ground
CAN HIGH shorted to pos
CAN LOW shorted to pos
Both wires shorted together
or resistive short on either wire to ground, POS or to themselves
or intermittent OPEN on these wires.

Now for the crappiness.....WHERE?!?!

I am new to learning about the CAN bus and other bus system in the car, BUT from what I've learned dealing with my G35 and 350z is that there are few components to keep in mind and where they are.

The buses in the car ALL have to get combined into a GATEWAY, and it is NOT the ECM. On our cars the GATEWAY is the Unified Control Module (90% sure of what I am saying) and that lives on the instrument cluster. Surprisingly enough the wiring diagram shows the UCM being connected to the A/C control module and also surprisingly doesn't control JUST the A/C (I don't recall ALL that it controls).


I've read here that replacing the A/C control module fixes stuff on the front of the instrument cluster, like lights, fuel gauge level, but am highly suspect of that. But THAT being said a used A/C control module is cheap on ebay and junk yards so MAYBE worth taking a look.


Do you go through car washes regularly? My G35 does and have narrowed down my issue (about 90% sure) to being some short in or around the transmission wire loom for the TCM , as I have similar issues and worse as you about an hour after going through the car wash. My car is in the shop :-) Hopefully the guy is good at finding CAN bus issues.

try to keep tabs as to WHEN it happens. Such as only on first startup of the day after sitting for several hours, every time you startup.

Maybe look up where all the modules are located and disconnect /reconnect each one that is easily accessed. In doing so you might get lucky and be just a loose connection between a pin and its connector, or you might SEE a bad wire.

I don't know the colors for the CAN bus wires...BUT they will be 2 wires that are twisted together. I believe ONLY network wires (CAN, LIN, etc) are twisted pair.

His '09 doesn't have a gateway, and on Nissan products which do (largely '14 up), it's called (oddly enough) the Gateway. On a few models there's a hybrid setup where the BCM actually contains a gateway, but that's unusual. On earlier models it's a single bus and the "anchors" are the BCM and IPDM, which contain the terminating resistors and are both alive even when the car is hibernating. CAN wires on a Nissan primary bus will usually be Blue and Pink, secondary buses divided from the primary by a gateway will be other colors.

On the OP's '09, the gauge driver and HVAC are both controlled by the same device, similar to the setup in Z's. So a failure or wiring issue with that one device (officially called the Unified Meter and A/C Amplifier) could be causing both issues. I'm a Nissan guy and I don't know if the Amp in a G has a ribbon cable like the Z cars do, but if it does, that's also a good candidate for the cause.

[cfauvel]

Awesome VStar650CL, thanks for the reply, corrections and explanations (not sarcasm).

[VStar650CL]