Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Chart B2 - BCM-To-IPC Communication Problem
You are at this chart because the odometer, with key on, read all zeroes and courtesy lights turned on when switch was actuated. These symptoms indicate a loss of BCM data communication to Instrument Panel Cluster (IPC), which is a result of one of several different possible problems.
- If ALDL connector cover is off or loose, this could cause a break in data circuit, cutting off BCM communication to IPC under certain electrical conditions. If so, securely connect ALDL cover and return to beginning of the SELF-DIAGNOSTIC SYSTEM CHECK.
- Isolates ALDL connector, the ECM and programmer from data circuit in order to determine location of fault. If odometer reads actual accumulated miles, the fault lies within network between ALDL connector, the ECM and programmer.
- Checks to see if fault is due to ECM and its related data circuits, or the programmer and its related circuits.
- Determines if fault is associated with IPC or BCM.
- Determines if fault is due to programmer, progammer's logic, or ground circuit No. 801 from Central Power Supply (CPS).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.