Crank Position & Tachometer Emulator
GM Gen III Engines in Jeep Vehicles
In 1996, Chrysler Jeep rolled out a more advanced version of their in-vehicle network called the Controller Area Network Bus, or CAN Bus system, over which data is shared between various electronic modules in the Jeep. One of those modules is the Jeep gauge cluster which uses a microcontroller to run the gauges.
TJ Wrangler & XJ Cherokee with 2.5L I4, 1997-2002
TJ Wrangler & XJ Cherokee with 4.0L I6, 1997-2004
TJ Wrangler with 4.0L I6, 2005-2006
JK Wrangler with 3.8L V6, 2007-2010
One largely successful strategy in retaining the factory gauges has been to keep the Jeep Powertrain Control Module (PCM) connected to the network as nothing more than a gauge mule, which is good for every gauge in the cluster except the tachometer, until now...
The Tachometer Emulator Module
Novak has developed this innovative emulator module that receives the tachometer output from a GM Generation III PCM. It then outputs the correct Crank Position (CKP) pulses to the Jeep PCM which then calculates the engine RPM's to be transmitted on the CAN bus to the Jeep gauge module.
This emulator module is built using an industrial duty processor making thousands of calculations per second to properly mimic the pulsetrain needed by the Jeep PCM to calculate and relay engine speed.
Jeep PCM's come in a few versions depending on the engine and model years of the Jeep. Choose the proper application to the right depending on your XJ, TJ or JK Jeep and its original engine.
Installation requires that the installer be able to competently join the wire leads to the existing Jeep wiring harness as directed in the instructions. This is best done with solder and thermal shrink wrap, followed up by wire loom. Physical installation into the Jeep engine bay is easy using the mounting tabs on the case of the module. Drilling is required.
GM Gen IV Caveat
The GM Gen IV PCM does not put out the same strong signal as the Gen III PCM's. As of this writing, we recommend this product only for Gen III PCM's.