Question about 2002 Jeep Grand Cherokee
New map sensor, new speed sensors(both)and wiring is good.
On most PCMs the PCM passes ground (input to PCM) out to the sensors. so if that ground is bad all are.
this is done on purpose, so the PCM can measure ground errors
and adjust sensor readings accordingly.
now Ill look yours up. since you stated its a 4.7L , most poster here
have not a clue to what is under hood.
my guess is the map is reading wrong?????????????
HINT1: when measuring ground attach your DMM to the battery minus
post and it will read 0 to 0.5v max for ground.
what did you read, as you said its not GETTING ground.
so what was the reading? 12v?
i take it you work with FSM/s and its schematics.
see chapter 8w-30 (wiring , Fuel-------) page 16-18
see that page.? page 17 is best.
see the 3 pins?
PCM pin 4 is ground to MAP pin 1. 0volts
PCM pin 17 is 5vdc power supply to Map and most be 5v (+- .25v)
PCM pin 27 is map out sig to PCM, (baro measurements)
the PCM master grounds (input)
are C1 pin 31 and 32.
they must read 0v to battery minus. KEY ON. or running.
page 8w30-6 see that.
wish i had the full symptoms. , no start, runs bad. what?
Posted on Apr 13, 2014
Testimonial: "thanks for input,yes it does start by holding throttle to floor wont idle plugs foul fuel to rich ecm not getting map sensor input no single have power 5 volts ,but only if i ground to battery,or other ground source,Haynes book says + lead #1termonal&-lead#3 i get-3mlivolts thanks for your time and appreciate your help"
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Posted on Jan 02, 2017
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Trouble Code: P0846
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