01 NO BUS problem
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Newbie
Joined: Jun 2018
Posts: 1
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Model: Cherokee (XJ)
01 NO BUS problem
Hey all,
The wife called and said that her xj won’t start and the cluster says “no bus” + gauges aren’t working. After towing the car home I checked for the sensors 5v ref circuit ( I checked at CPS) nothing - I checked the CMPS - nothing. I then checked for 5v directly at the PCM- nothing. I verified power and ground and the PCM wasn’t getting power on C1/2 “FUSED IGNITON SWITCH OUTPUT” I checked the fuse and it’s fine. Using a fused jumper, I connected the battery positive to C1 pin 2 and the PCM came back to life but it still wouldn’t start.
NOW it looks like the PCM doesn’t send commends to the fuel pump relay as well as the ASD relay..
any input?
The wife called and said that her xj won’t start and the cluster says “no bus” + gauges aren’t working. After towing the car home I checked for the sensors 5v ref circuit ( I checked at CPS) nothing - I checked the CMPS - nothing. I then checked for 5v directly at the PCM- nothing. I verified power and ground and the PCM wasn’t getting power on C1/2 “FUSED IGNITON SWITCH OUTPUT” I checked the fuse and it’s fine. Using a fused jumper, I connected the battery positive to C1 pin 2 and the PCM came back to life but it still wouldn’t start.
NOW it looks like the PCM doesn’t send commends to the fuel pump relay as well as the ASD relay..
any input?
Member
Joined: Mar 2015
Posts: 111
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Year: 60th Anniversary
Model: Cherokee
Engine: 4.6
If you have no power at PCM C1 pin 2 without a jumper and issues with ASD relay activation I would literally follow (or do a continuity check) the wire from the junction block to the pcm. You may be surprised and find a melted wire or three. Maybe a bad splice?
I would confirm circuit integrity before buying other parts. Thats just me?
I would confirm circuit integrity before buying other parts. Thats just me?
CF Veteran
Joined: May 2012
Posts: 7,965
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From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
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