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ptimhere
October 13th, 2017, 11:00
I've been trying to pin down a no start no bus condition. General consensus was CPS, so got a new one and the condition continued.

I was able to crawl under the machine today with a meter and these are the readings I got -

old sensor - infinite resistance, 1 volt dc, no ACv
new sensor - 4.7 on 200K ohm scale, 1 volt dc, no ACv

If I understand those readings correctly, I'm chasing the wrong problem and have to figure out why I'm only getting 1 DCv to the sensor to start with.

Any thoughts?

8Mud
October 13th, 2017, 17:03
I think I need the model year. Could be another sensor (mostly) shorting out. The sensors that are bundled together on the same supply voltage, changes some in different model years.

Unplug the CPS and then check the supply voltage, next unplug the cam sensor, then maybe the speed sensor and check your supply voltage.

ptimhere
October 13th, 2017, 17:18
Ah, I forgot to include that, meant to put it at the top of the post - 2001 Cherokee Limited.

The supply voltage at the harness, disconnected from the sensor is the same as when the sensor is connected - 1 volt, DC.

8Mud
October 14th, 2017, 12:01
Pretty sure the CPS, Cam Position Sensor, MAP and TPS all share the same 6 volt supply.

I'd unplug them one at a time and test the supply voltage. If you get lucky and unplug the right sensor your six volts and bus may come back.

90xj06
October 14th, 2017, 14:15
can you get a scan tool to read the pcm? i only mention this as i recently watched a video that had a bad relay that would drop the voltage down to about 1v and would keep the pcm from turning on and giving essentially the no bus error to the cluster.

it was the main relay for the ecu. powerlatch or B+ relay. not sure of the naming on the 01

ptimhere
October 15th, 2017, 04:05
The scan tool does not connect to the pcm at all. I'm trying to check sensors to see if there is a bad one on the loop.

I'm very interested to know what relay that is. I will have to go exploring some more.