Honda Network Map
Honda introduced CAN on US-market vehicles in the mid-2000s using a dual-bus architecture: a 500 kb/s high-speed powertrain/chassis CAN and a lower-speed body/comfort CAN. The PCM typically acts as the gateway between buses, with dedicated gateway modules appearing on some later models. Pre-CAN vehicles used Honda proprietary serial and K-line protocols. Aftermarket accessory integration (especially remote starters, alarms, and audio) has historically caused network faults when installers tap incorrect circuits or splice into the bus improperly.
Testing values and scope patterns are universal — they live on the main CAN playbook. This page is what's specific to Honda: the buses, where the terminators live, and what breaks. Tap any era to explore it — network map, testing guide, failure patterns.
2003-2012
PCM-gateway architecture
Some models retain K-line/proprietary serial for specific modules into this era.
| Bus | Speed | Carries | DLC access | Terminators live in |
|---|
| F-CAN | 500 kb/s | Powertrain (PCM, TCM), ABS/VSA, SRS, EPS · F-CAN is Honda's designation for the main high-speed CAN bus; PCM acts as gateway to B-CAN | DLC pins 6 and 14 | not independently confirmed |
| B-CAN | — | Body/comfort systems: HVAC, audio, navigation, door modules · Lower-speed body/comfort bus; not all models/trims have B-CAN, base models may be F-CAN only | Via PCM gateway | not independently confirmed |
GatewayPCM (Powertrain Control Module)
Explore this era ⤢2013-present
Dedicated gateway introduction and expanded architecture
Module counts increased with Honda Sensing and driver-assist features; some models add additional sub-buses for cameras/infotainment not accessible via DLC.
| Bus | Speed | Carries | DLC access | Terminators live in |
|---|
| F-CAN | 500 kb/s | Powertrain (PCM, TCM), ABS/VSA, SRS, primary chassis/safety systems | DLC pins 6 and 14 | not independently confirmed |
| B-CAN | — | Body/comfort: HVAC, audio/infotainment, navigation, door modules | Via gateway | not independently confirmed |
GatewayPCM or dedicated Gateway module (model-dependent)
Explore this era ⤢What breaks on Hondas
Aftermarket audio/alarm/remote start CAN tap failures
Poorly-installed aftermarket remote start, alarm, or audio systems tapping the bus (at DLC, PCM connectors, behind the gauge cluster, or at the head unit) cause no-start, multiple communication codes, or intermittent bus failures. Check for spliced wires, T-taps, or non-OEM CAN adapters.
EPS module CAN communication loss
Electric Power Steering (EPS) modules on F-CAN develop internal failures causing bus communication loss, especially 2006-2011 Civic and CR-V. Causes EPS warning light, loss of power assist, and often multiple F-CAN codes. A failed/shorted EPS unit can pull down the entire F-CAN bus. Verify power and ground before condemning the module.
The bench — what to test with
Digital multimeter with a manual 200-ohm range$40-100
Terminator resistance (~60 ohms), idle-bias voltage, ground-drop, and split-half isolation are all DVOM jobs — a cheap meter genuinely resolves 60 vs 120 vs 0 ohms and 2.5V bias, solving most Honda CAN faults if you know the target numbers.
2-channel oscilloscope$150-600 for a capable 2-channel scope
The one thing a DVOM can't replace: it shows mirrored differential edges, reflections from bad aftermarket stubs, a babbling node, and reduced amplitude from a missing terminator — the intermittents a meter averages away. You do not need a flagship unit for 500 kb/s CAN.
DLC breakout box / backprobe pin set$20-150
Lets you probe pins 6/14/4/5 and body-module connectors cleanly without piercing insulation, keeping you honest about which pins you're on and preventing the corrosion/splice faults you're hunting.
Bidirectional scan tool (HDS or capable HDS-class pass-thru)$300-2000+ depending on OE vs aftermarket coverage
Needed to read the scan-tool module list (single vs grouped dropout is your fastest diagnostic), reach behind-gateway B-CAN modules, run bi-directional tests, and do VIN-locked programming (immobilizer/BCM/gauge) — Honda has no security gateway so there's no unlock wall, but you still need the tool for programming and B-CAN routing.
Scan-tool access
Honda does not use a security gateway; scan tools generally have full access without unlock procedures. Pre-CAN vehicles use Honda proprietary serial and ISO 9141 K-line protocols (DLC pin 7). ISO 15765 (CAN) is standard on CAN-era vehicles. F-CAN is accessible at DLC pins 6 (CAN-H) and 14 (CAN-L). HDS (Honda Diagnostic System) or a compatible pass-thru/bi-directional tool is required for most programming and some special functions; some modules (immobilizer, BCM, gauge) require VIN-locked programming.