SwapSync

Swap the engine.Keep the gauges.

In development · first profile passed the bench test

SwapSync is a CAN translator for engine swaps where both the engine and the chassis run CAN bus. It reads the new engine's bus, stands in for the old engine computer on the chassis bus, and keeps the factory cluster, warning lamps, radiator fan, ABS and cruise control working.

RPM × 1000 848
Tach · from 0x280
SwapSync · TDI → JK● RX/TX
0x28001 00 40 0D 00 00 00 00 engine RPM · LE ÷ 4 = 848
0x30800 03 50 00 01 00 00 00 Jeep tach · BE raw = 848
0x28800 B0 00 00 00 00 00 00 coolant · raw × 0.75 − 48 = 84.0 °C
0x6087C 00 00 00 00 00 00 00 Jeep coolant · raw − 40 = 84 °C
Simulated. Real encodings from profile 01, checked against the ECU's own measuring blocks.
COOLANT °C 84
Coolant · from 0x288
The problem

Pull the engine computer and the truck goes deaf

A modern chassis expects to hear from its own engine computer. Take it out for a swap and every module that listened to it starts setting codes and falling back to failsafes.

15/48

CAN-C messages that vanished on the 2010 JK with the PCM unplugged. SwapSync sends all 15 back, with the right rates, counters and parity bits.

0x1010x2100x2120x2180x3080x3120x3380x3D00x4150x4180x4A00x5200x6080x6FA0x6FE
Cluster

Dead tach, no coolant gauge, warning lamps that never light or never go out.

ABS

Logs U0100 and U0401 for lost or invalid engine data, and traction control quits.

TIPM

Runs the radiator fan flat out because nobody is asking it for anything.

New engine

Misses the road speed, cruise lever and battery voltage it used to get from its old chassis, so its own cruise stays blocked.

How it works

One board. Two buses. Both directions.

SwapSync runs on a dual CAN board. One sits on the engine's bus, the other on the chassis bus where the old engine computer used to be. A few chassis switches wire straight to the board.

Engine bus → chassis

Gauges, lamps, modules

  • Tach and coolant gauge from the engine's own data
  • MIL, oil pressure, high coolant and glow-plug lamps
  • Radiator fan requests (off, low, high) from engine coolant
  • Fuel flow for the cluster's mileage readout
  • Torque and pedal data so ABS and traction control stay happy
  • Brake, clutch and cruise lamp frames, rebuilt from hard-wired switches
Chassis → engine bus

What the engine needs back

  • Road speed from the chassis ABS
  • The chassis cruise buttons, translated into the engine's own cruise lever
  • Battery voltage from the board's own sense input
  • Brake and clutch signals into the engine ECU through relays
  • Traction control torque limits, once tested
Requirement: CAN on both sides

SwapSync only works when both the engine and the chassis use CAN bus. It translates between two networks, so each side needs one.

A mechanical engine like a 12-valve Cummins or a 4BT, or an older chassis that runs its gauges off hard-wired senders, has no CAN messages to translate.

Fail-safe by design

When data goes bad, it fails toward safe

Every output has a defined behavior for missing, stale or implausible data. When in doubt: cool harder, warn louder, drop cruise.

Fan high

Engine coolant data goes stale or implausible

Requests the fan on high, same as the TIPM's own failsafe.

MIL on

Engine fault state is unknown

Lights the check engine lamp instead of hiding a problem.

Early warning

Coolant passes 110 °C

Pegs the gauge into the cluster's high-temp lamp before the engine is in real trouble.

Cruise off

Brake or clutch pressed, or the chassis side goes quiet for 500 ms

Cancels or switches off the engine's cruise.

Ignored

A cruise button is held more than 3 seconds

The button is suppressed until it's released.

Refused

Settings changed with the engine running

Settings change only with the engine stopped. Pins and safety values stay locked. A dead or unwired board leaves the engine's cruise blocked.

Profiles

One translator, many swaps

The translator itself holds no vehicle values. Each engine and chassis pair is a profile: the decoded CAN facts for both buses, plus the owner settings. New swap, new profile, same board.

SWAPSYNCPROFILE 01 · FW 0.1.0
VW TDI (BRM) ▸ Jeep Wrangler JK
Engine2006 VW 1.9 TDI · EDC16
Chassis2010 JK · manual
PCM messages15 / 15 reproduced
Gauges + lampsVerified on vehicle
CAN-C sendersAll mapped
HardwareDual CAN board + I/O board
Bench testPassed · 2026-10-22
CruiseTo test in the Jeep
SWAPSYNCPROFILE 02 · OPEN
Your engine ▸ Your chassis

A Cummins in a van, a TDI in something other than a Jeep, a late-model diesel in another CAN-equipped chassis. Tell me what you're swapping and what quit working. The next profile goes where the demand is.

Settings and diagnostics

Plug in a laptop. See everything.

The SwapSync page opens in Chrome, Edge or a current Firefox with no internet and nothing to install. Plug into the board's USB port, click Connect, and you get live values, the translator's own fault history and every adjustable setting with its safe range.

swapsync_page / index.html · USB connected
RPM848
Coolant84 °C
Speed0 km/h
Battery14.1 V
FanOFF
CruiseOFF
Example values for illustration.
Build log

Where it stands

Built in the open, dead ends and all. Every decoded signal is logged with its evidence before it goes into the translator.

092926
Immobilizer handshake

The key module accepts SwapSync in place of the PCM, every time.

100826
Gauges and lamps verified

Every lamp and gauge the PCM drove, checked on the Jeep. Hard-wired inputs designed.

101526
Named SwapSync

The TDI-JK translator becomes the first profile of a general product.

101826
Engine ECU bench test

The TDI ECU reads SwapSync's road speed and cruise frames on the bench.

102226
Translator bench test passed

The board and its bolt-on I/O board on a bench rig with both buses live. Inputs, outputs, both buses, fail-safes, the settings page and bus-off recovery all passed. Cruise waits for the real switch pod in the Jeep.

------
In the Jeep

The swap, then the cruise checks parked with the engine running, before the first drive.

------
On the road

Cruise bring-up and road testing, then traction control.

Get updates

Doing a swap? Write it up.

SwapSync isn't for sale yet. Fill out the repair order with your combo. It decides which profile comes next, and you'll hear first when boards are ready.

Shops doing more than one swap a year: say so. Install support and multi-unit pricing are on the table.

Repair orderRO #SS-0001
Customer type
Complaint
Cause

Chassis lost its engine computer. The modules aren't hearing what they expect on the bus.

Correction

SwapSync profile for your engine and chassis.

Example answers filled in