Wiring Harness & PCM Programming Services

for the

GM Generation III+ Engines

One of the most significant things an installer can do to speed the conversion process along and keep the headaches at bay is to have their factory GM harness simplified and modified. Novak has gotten this wiring process and PCM programming down to a science. To place an order or for more information, please call our sales team.

Wiring Harness

Typically, the conversion installer will get the factory engine harness from the donor vehicle. This will include every wire and connector between the PCM and the engine's sensors (Oxygen, Throttle Position, Crank Position, etc.) and the active systems (coil triggers, injectors, IAC, etc.).

Novak can simplify this harness, removing unnecessary circuits, consolidating circuits, rerouting and labeling for a simpler 5-6 wire hookup into any Jeep.

Vehicle Speed Sensor

This sensor will allow you to run a conventional cable drive speedometer and send critical speed data to your GM PCM for proper powertrain operation.

Harness Mods at a Glance:

• Install DLC port for installation in the Jeep cab
• Provide fuel pump relay and simplified fuel pump circuit
• Provide a simplified and water-tight power distribution center with standard ATC-style fuses and relays
• Simplify main 12V and main Ground circuits
• Front & rear O2 sensors will be retained. Rear O2 sensors may be programmed out if requested by the customer and permitted by your jurisdiction
• Provide an easy-to-install MIL lamp
• Provide VSS leads
• Fully inspect all circuits
• Install a standalone air conditioning control circuit
• Provision for standard shift or automatic shift (typ. 4L60E) transmissions
• Minorly damaged harnesses can be repaired. For more extensive damage, reasonable additional costs will be determined
• Five wire hookup (manual trans option) or seven wire hookup (automatic trans option)
• Park / Neutral safety switch will be added for Jeeps that originally did not have this circuit
• All trunks and branches are arranged and wrapped with new split-loom and made to more appropriate, standardized length for Jeep vehicles.
• A tachometer signal wire, required on many aftermarket tachometer solutions.
• If you are wishing to keep your 1996-2006 XJ / TJ factory tachometer, consider Novak's tachometer emulator module, as seen here.

Pictured left is the extra heavy-duty relay used in our rebuilds for radiator fan control.

Identifying your GM PCM

GM Generation 3+ PCM's come in three major styles as follows:

Make sure your PCM and harness are compatible, if they were not pulled from the same vehicle. Intermixing PCM's and harness can yield unexpected results. Always consult us on this before moving forward.

Note: Wiring harness builds during some seasons may require more time than our usual quick turn-around. If time is of the essence, contact us directly for current lead times.

Disclaimer: Any modifications to the Novak harness as provided, without the express written permission of Novak, will void the warranty. This includes any cutting of wires, modification of lengths, or changes to connectors - even if they are part of non-utilized circuits such as unused emissions, evap, or other features. If these are unused in your situation, leave them intact and tie them securely against the harness.

Shipping Instructions

Please see our Contact page, where you'll find our physical address to which you can send your harness and/or computer. When shipping, we recommend you insure your harness for the typical value of a new replacement harness, which is commonly ~$900 and computer for ~$250. Please include your name and contact information with your shipment so we can reach out to finalize your order.

Please do not send anything other than the harness with your shipment. We do not need the throttle pedal, fuse box, battery terminals, or any other sub harnesses, just the engine wiring harness. If you are not sure if it is part of the engine or GM chassis harness, send it and we'll discard as necessary.

For inquiries and orders, contact our sales team at the number listed on the Contact page. Accurate lead times will be provided upon inquiry.