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Patrick

Patrick 11/21/2021

2001 Jeep Grand Cherokee Limited 8 Cyl 4.70L

Engine

I have a no bus display and no crank

This problem is common with this vehicle but I can't find a definitive answer. I am looking for info and the wireless control module like where it is located and how to reset or bypass the bcm possibly. I've just replaced a newly flashed pcm, starter, ignition, ignition control module and TPS. Any info, diagrams pics or something else would be greatly appreciated!

1 Answer


Jimm

Jimm 4/12/2022

There are 2 types of NO BUS conditions.

#1. A no bus appears on the dash, but the engine runs fine. This is almost always a dash cluster problem

#2. A no bus appears on the dash and the engine does NOT run. This is your problem.
A good majority of times, it is a failed (shorted) crankshaft position sensor causing this. Theoretically, any 5 volt engine management sensor can short and cause this problem, but the crank sensor is the most suspect.

Try this simple test. Get under the vehicle and remove the connector for the crank sensor (on transmission bellhousing). NOW check the dash. If the NO BUS is gone, you have confirmed that the problem is the crank sensor. Try this with each of the 5 volt engine management system sensors.

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