A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- Power or ground of this control unit (fuse)
- CAN bus connector or wire
- The engine ground is loose or corroded
- The wiring harness has chafed on the alternator bracket or an A/C line
- Low battery voltage
- The control unit itself
What you can do yourself
- The transmission may go into limp mode: shifts are harsh or the car drives in one gear. You can drive gently for a short distance.
- Check the battery and terminals: at low voltage control units lose communication.
- Check this control unit’s fuses.
- Check the engine ground: the ground strap is tight on the engine and on the body, with no corrosion. Per a GM bulletin, a loose ground sets many communication codes at once.
- Inspect the wiring harness by and under the alternator: per a GM bulletin it chafes on the alternator bracket.
- Look at the codes of the other units: if communication is lost with several units at once, look for a common cause (ground, power, bus wire) rather than replacing units.
- If the code is only in history and the car runs normally, clear it and see whether it comes back. If it doesn’t, no repair is needed.
Stop and don’t drive on if:
- The instrument panel went dark or many warning lights came on at once
- Power steering is gone or the brakes don’t work as usual
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
The bus number (CAN 2, CAN 3) is GM’s internal numbering: in new cars the units are split across several buses joined by a gateway module. This is the GM meaning (Chevrolet, Cadillac, GMC). On other makes this number means something else: if your car isn’t made by GM, change the make at the top.
Source: GM 23-NA-102 (Silverado, Tahoe, Yukon, Escalade 2022–2024), static.nhtsa.gov
On Oleg’s website:Car wiring repair ↗
The explanation comes from the error code reference in the AvtoElektrik PRO app.