Ram Network Map
Ram trucks split from Dodge branding around 2009-2011 and share Chrysler/FCA/Stellantis CAN architecture. They use a dual-bus design: a high-speed powertrain/chassis bus at 500 kb/s on DLC pins 6/14 and an interior/body CAN at 125 kb/s (pin assignment varies by draft; see conflicts_dropped), with a gateway translating between buses for scan-tool access. The Totally Integrated Power Module (TIPM), under hood on the driver side, serves as central power distribution and is a known failure item. Later models (roughly 2018+) add a security gateway requiring authentication for module programming and some diagnostics.
Testing values and scope patterns are universal — they live on the main CAN playbook. This page is what's specific to Ram: the buses, where the terminators live, and what breaks. Tap any era to explore it — network map, testing guide, failure patterns.
2003-2008
Early CAN adoption; some 2002-2003 models may still use PCI bus for certain modules.
| Bus | Speed | Carries | DLC access | Terminators live in |
|---|
| powertrain/chassis CAN (see conflicts_dropped for bus name) | 500 kb/s | PCM, ABS, instrument cluster | DLC pins 6/14 | not independently confirmed |
| interior/body CAN (see conflicts_dropped for bus name) | 125 kb/s | Body control (BCM), radio, HVAC, overhead console, door/accessory modules | DLC pins 3/11 | not independently confirmed |
GatewayBody Control Module (BCM), left side of dash
Explore this era ⤢2009-2017
TIPM serves as central fuse/relay/power distribution center.
| Bus | Speed | Carries | DLC access | Terminators live in |
|---|
| powertrain/chassis CAN (see conflicts_dropped for bus name) | 500 kb/s | PCM, ABS, instrument cluster, airbag control, TCM | DLC pins 6/14 | not independently confirmed |
| interior/body CAN (CAN IHS) | 125 kb/s | Radio, HVAC, steering control module, door modules, overhead console, Uconnect systems | DLC pin assignment unresolved across drafts (see conflicts_dropped) | not independently confirmed |
Gatewaygateway identity/location for this era unresolved across drafts (see conflicts_dropped); TIPM present as power/fuse/relay center
Explore this era ⤢2018-present
Security gateway requires FCA/Stellantis authentication for module reprogramming and some diagnostics. Some models add an Ethernet backbone for infotainment/ADAS. 2500/3500 HD share similar architecture.
| Bus | Speed | Carries | DLC access | Terminators live in |
|---|
| powertrain/chassis CAN (see conflicts_dropped for bus name) | 500 kb/s | PCM, ABS, TCM, instrument cluster, airbag control | DLC pins 6/14 (via security gateway) | not independently confirmed |
| interior/body CAN (CAN IHS) | 125 kb/s | BCM, Uconnect radio, HVAC, steering wheel/control module, door modules, lighting | DLC pins 3/11 (via security gateway) | not independently confirmed |
GatewaySecurity gateway (name/location varies by draft; see conflicts_dropped)
Explore this era ⤢What breaks on Rams
TIPM water intrusion
2010/2011-2016 TIPM in the engine compartment (driver side) is prone to water intrusion through seal failures, causing erratic module communication, phantom module faults, and dropouts. Water can wick down harnesses. Known across Chrysler/Dodge/Ram of this era with multiple TSBs and class-action attention. Often sets U-codes in multiple modules simultaneously.
Trailer wiring interaction on powertrain/chassis bus
Factory and aftermarket trailer wiring (especially the 7-pin connector) can induce shorts or voltage/ground faults that disrupt CAN communication, commonly throwing ABS and traction control faults. Common on 2009-2018 models; inspect connector and harness routing.
Aftermarket radio/accessory CAN installation faults
Incorrectly tapped interior CAN wiring during aftermarket radio, amplifier, remote start, or alarm installs (especially on Uconnect-equipped trucks) causes bus shorts, contention, or intermittent communication faults. Verify CAN-compatible harnesses and bypass modules.
The bench — what to test with
Quality DVOM with a 200-ohm manual range$40-120; a cheap-but-decent meter with a real manual ohm range genuinely suffices here
For terminator resistance (~60 ohm check), idle bias voltage, and split-half short/break hunting, a plain meter does honestly 80% of Ram CAN diagnosis — a manual low-ohm range and good leads matter more than brand.
2-channel oscilloscope (automotive)$150-400 gets a usable 2-channel handheld/USB scope; you do not need a flagship lab scope for slow CAN
The scope is the only thing that shows differential waveform quality — termination ringing, stuck-dominant, single-wire fallback, and babbling nodes that a DVOM's time-averaged number can't reveal; it also proves a gateway-hidden bus is physically alive.
DLC breakout box / backprobe pin set$15-80 for backprobe leads; more for a full breakout box
Lets you reach pins 6/14 and 3/11 and backprobe module connectors cleanly without spreading or piercing terminals — essential for the gateway-hidden-bus and split-half tests. Never pierce CAN wire insulation.
Factory-level or FCA/Stellantis-licensed scan toolVaries widely; budget for gateway authentication/subscription, not just the tool
For 2018+ trucks the security gateway means bi-directional tests and programming — and sometimes basic reads — require FCA/Stellantis authentication; independent tools without licensing see only a gateway-translated subset.
Battery maintainer/stable power supply$50-150
Marginal voltage causes false scan/gateway glitches and is mandatory during any programming; keeps your diagnosis honest.
Scan-tool access
Pre-2003 Ram used PCI bus or early J1850/ISO 9141; CAN adoption began around 2003-2004. Later models (2018+) use a security gateway requiring authentication for module programming and some advanced/bi-directional functions — use a factory scan tool or aftermarket tool with FCA gateway licensing; independent tools may see only a gateway-translated subset. Scan tool must support both buses simultaneously for a global scan.