Detroit Series 60 Swap Harness — New Cascadia 2018-2021 · Communication Module Included

The New Cascadia 2018-2021 runs a fully multiplexed, high-speed J1939 network (500 kbps). No Series 60 speaks that language from the factory:

• The 12.7L with a DDEC IV ECM communicates over the older J1708/J1587 protocol → it needs a J1708 → J1939 converter so the cab can understand it.
• The 14.0L with a DDEC V ECM does speak J1939, but at 250 kbps → it needs a bidirectional 250 ↔ 500 kbps converter to sync with the New Cascadia's network.

That is why this product includes the correct module for the variant you choose, already connected to the harness, configured and tested by our team before shipping. Nothing to buy separately, no configurations to figure out: pick your ECM and receive a complete working system.

1. Engine harness (engine ↔ cab) — connects the Series 60 ECM to the main components: batteries, starter motor, ignition signal, fan clutch, coolant level sensor and air conditioning.

2. In-cab harness — connects the New Cascadia cab to the engine's electronic controls: fully functional accelerator pedal, dash with active gauges and warning lights, and general ECM ↔ cab communication through the module.

3. Communication module — matched to your variant (J1708→J1939 for DDEC IV, or 250↔500 kbps for DDEC V), integrated into the harness, configured and tested by CTS before shipping.

Technical note: the DDEC IV harness carries more physical wiring (the older protocol requires more dedicated circuits); the DDEC V harness is more compact because almost everything travels multiplexed over the J1939 network. Both use the same material grade and the same manufacturing process.

• Shops doing Detroit Series 60 swaps on New Cascadia 2018-2021 platforms
• Owner-operators who prefer the Series 60 (repairability, parts cost, reliability) over the original DD13/DD15
• Fleets repowering New Cascadias with remanufactured Series 60 engines
• Mechanics who need the electrical and communication side of the swap solved and tested, without experimenting with converters

• SAE J1128-certified automotive wire — resistant to engine-compartment heat, oil, diesel and continuous vibration
• 18 AWG main wiring · 16 AWG injector wiring
• Crimped terminals with verified pull-test · corrugated loom + heat shrink at branch points
• SKU and version marked on the harness · quality inspection certificate (QC pass)

• Does not include the ECM (if you need one programmed, contact us)
• Does not include engine sensors, injectors or the injector sub-harness
• Does not include the chassis harness or transmission harness
• Does not include the mechanical side of the swap (mounts, fuel lines, cooling)

• Every system is built, integrated and tested to order — message us on WhatsApp to confirm the current build time before buying if your truck is down
• U.S. domestic shipping via UPS

12-month warranty against manufacturing defects from the ship date, covering the complete system (harnesses + integrated module). It does not cover damage from incorrect installation, misuse, or failures external to the system (ECM, sensors, external short circuits, mechanical conversion errors).

Why can't I use the Cascadia 2009-2017 harness in a New Cascadia?
Because they are different networks. The classic Cascadia runs J1939 at 250 kbps with J1587 support; the New Cascadia runs a 500 kbps multiplexed network. The wiring, connectors and communication are different — that is why this is a specific product for 2018-2021.

Does the module come loose for me to connect?
No. CTS integrates the module into the harness, configures it and tests the complete system before shipping. A wrong connection can damage the ECM, the harness or the module — so we deliver it working, not in pieces.

What is the difference between the DDEC IV and DDEC V harnesses?
The DDEC IV uses the older J1708 protocol and requires more dedicated physical wiring plus the J1708→J1939 converter. The DDEC V already speaks J1939 (at 250 kbps) and its harness is more compact because the information travels multiplexed; it only needs the 250↔500 kbps speed converter. Both arrive complete and tested.

How do I know if my engine is DDEC IV or DDEC V?
The 12.7L uses DDEC IV; the 14.0L uses DDEC V. If in doubt, send us a photo of the ECM label on WhatsApp and we will confirm it before you buy.

Do you have the version for the Cascadia 2009-2017?
Yes — it is here, with options for DDEC IV (with or without the factory-steering-wheel module) and DDEC V.

CTS (Car Tuning Star) is a technical laboratory specializing in heavy-duty trucks: ECM programming, computer repair, custom harness manufacturing, electrical diagnostics and general mechanics. Technical support in English and Spanish via WhatsApp, phone and email — we speak shop language, because the CTS team comes from the shop.