I was driving to work the other day and the yj just shut off on me, the check engine light came on and when i turned off the ignition and turned it back on the check engine light was gone. i checked for spark and there was none. i've replaced the distributor cap, distributor rotor, ignition coil and the crankshaft position sensor and still no change. frustrated i went and bought an OBD 1 reader and it threw 4 codes at me the first was that the o2 sensor was shorted out and i looked and the wires had melted against the engine block exhaust so as a temporary fix i wrapped the wires in electrical tape and the code for the o2 sensor disappeared. the other codes are (code 22) - coolant temp sensor signal voltage out of range (code 23) - intake air, air charge or throttle throttle body temp sensor voltage signal out of range (code 24)- throttle position sensor signal voltage out of range. Would any of these codes cause the yj to crank but not start?
Jeep yj crank but no start
- Thread starter akopp1652
- Start date
Flyer58
YJ Enthusiast
Try removing and spraying electrical contact cleaner on all relays, fuses and the big plugs on the ECU. It's a pain but corrosion can sink in deep and cause this many problems. I've had several intermittent electrical problems and found some contacts looking like they had barnacles growing on the copper connectors.
Superbird17
Member
Yes on all 3 of the named sensors.
Does the jeep turn over, but just won't start? or are you getting silence when turning the key?
Please post your finding of the problem. It helps others that may have the same issue in the future.
Thanks
Does the jeep turn over, but just won't start? or are you getting silence when turning the key?
Please post your finding of the problem. It helps others that may have the same issue in the future.
Thanks
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NO car told , just YJ, can I buy a year???????????? so i can read you FSM pages to you and not lie?
2.5Liter engine or?
did you check all fuses first.? the PCM must have full DC 12vdc power to run all sensors. okay?
fuse 1 and 5 not blown, at least. at PDC
it stalls and spark ended, so #1 reason for that is ASD relay is not staying engergized.
what reader was that, love to know that? plugged in where, the PCM ,box, side plug DLC?
02 shorts the PCM drops the ASD like hammer,
ECT sensor , wires bad or it is bad, IAt SENSOR SAME,
iD SAY WIRING TO BOTH BAD, OR THE Voltage to it wrong or dead. power pin on them dead.
there are like 8 reasons, ASD goes off line, i made page to show them all
all I know is YJ jeep and not the old 87 carb.
here is my 95 page on ASD, it condenses 3 books and vast pages to 1 page, why does ASD go offline, also swap it and horn relay they are the same.
I will now answer the why question
the PCM does not allow the car to catch fire is why, called crash and burn
if the PCM sees gross errors on the output side of the ASD , this is called overload and it shuts down the ASD.
all EFI gas car engines made do this, on Jeeps it ASD, (the name) and by law. Ever see a car fire,,fuel fed, it is not a pretty site.
if the PCM detects spark bad, it cuts fuel fully, via disabled injectors and on this jeep if ASD drops, spark and fuel pump are now dead.
by 100% design and by USA laws (on topic) study how EFI works.
the 3 sensor bad , just a bad ground to all 3 will make them all read high voltage (wrong)
the ground on mine is called S114, (schematics page FREE FSM)
this bad kills dead too, the CMP
G104to PCM? bad? goes to 3 PCM ground pins, and must be good or all sensors go dead.
if G104 good and all fuses good the PCM then sends its own sensor ground to S114 feed (gnd)
S114 runs the crank sensor too, and not both are dead, CMP and CKP and by pure logic there can be no spark ever.
the PCM sends 8vdc (reg) to other sensors. crank ,CAM and speed VSS. on my 95. YJ
S113 and S114 are created by the PCM , so the PCM grounds (all) and fuses must be good or none of this EFI stuff will work. at all
fill out your profile please
tell year
tell driveline there, what engine , what transmission.
and mods ,known.
tell year
tell driveline there, what engine , what transmission.
and mods ,known.