Engine shut off. I now have. Zero spark.

MATTHEWALANWOLLETT

MEMBER
1996 JEEP GRAND CHEROKEE
235,431 MILES

O2 wires where cut. I pushed on exhaust and harness side of o2 wires sparked and the jeep shut off. I now have. Zero spark.

The spark happened when the harness side of the 02 wires touched the heat shield the Jeep cut off . Immediately. I started trying. To. Figure it out. Other symptoms are. No voltage guage, fuel pump seems to run non stop. 3.7 volts to coil. Asd relay terminal 16 has 4.2 volts key on and 18 has 10/12 volts key on both loose voltage when key is off. I tried a different pcm and all symptoms remain. I changed cps sensor and symptoms remained. Im baffled and my obd2 port has never worked. Theres no check engine light. Im a ase tech but very weak electrically. Im so confused

4 Replies

CARADIODOC

MECHANIC
33,873 POSTS

You blew the fuse feeding the ASD relay. That circuit feeds the O2 sensor heaters, ignition coil, alternator field, and injectors.

You can prove this by measuring the voltage to any of those points. Sorry I don't know the wire color but it will be the same to all of those parts. You should see 12 volts there for one second after turning on the ignition switch, then again during engine rotation, (cranking or running). A test light works better than a digital voltmeter because most voltmeters don't respond fast enough to show that one second pulse.

You know the crankshaft position sensor didn't get damaged but now that you replaced it, was there a spacer on the end to set the air gap? It would be either a piece of thick paper stuck on the end or a thin plastic rib molded to the end.