Blowing EFI Fuse (shorted O2 Sensor??)

[98 SNAKE EATER]

OK, I just got done replacing the entire exhaust system from the Y-Pipe all the way back

Went to start her up and she cranked, but didn't start

EFI fuse was blown, replaced it and it blew again as soon as I turned the key

Since the only wiring I messed with were the O2 sensors, I checked the harness at both sensors for kinks and all looked good....

Disconnected the rear O2 sensor and she started right up

Plugged it back in and she blew the fuse again

Disconnected both O2 sensors and checked the heater circuits with my Ohm Meter as per FSM....

Both read fine at 14ohms across the HT and B+, however, the rear O2 shows continuity across the HT and the other two wires that typically aren't tested

Checked for continuity on the same wires on the front O2 sensor and both wires are open

So I'm guessing the rear O2 sensor somehow got shorted when I removed it from the old exhaust

It was rusted to hell and I had to use an air hammer to chisel the studs off

Anyways, has anyone else run into this problem before?





Rick

 

[jonheld]

Seems like you already have your answer Rick. I'd replace them both, but that's me.

 

[thadscottmoore]

had the same problem with mine. turned out, my old exhaust mount had broke - causing the exhaust pipe to short out the rear wiring harness- burning the wires all the way back to the plug in connection- melting all the sensors associated. The FJ80 would run, but- the shifter would not shift without pushing the shifter over-ride button. But, the ECU fuse would pop as soon as you stuck one in. New harness and new sensors- no problem since.

OK, I just got done replacing the entire exhaust system from the Y-Pipe all the way back

Went to start her up and she cranked, but didn't start

EFI fuse was blown, replaced it and it blew again as soon as I turned the key

Since the only wiring I messed with were the O2 sensors, I checked the harness at both sensors for kinks and all looked good....

Disconnected the rear O2 sensor and she started right up

Plugged it back in and she blew the fuse again

Disconnected both O2 sensors and checked the heater circuits with my Ohm Meter as per FSM....

Both read fine at 14ohms across the HT and B+, however, the rear O2 shows continuity across the HT and the other two wires that typically aren't tested

Checked for continuity on the same wires on the front O2 sensor and both wires are open

So I'm guessing the rear O2 sensor somehow got shorted when I removed it from the old exhaust

It was rusted to hell and I had to use an air hammer to chisel the studs off

Anyways, has anyone else run into this problem before?





Rick

 

[p8nt]

I just bought denso O2s from rockauto.com. About $130 for the pair.

 

[98 SNAKE EATER]

had the same problem with mine. turned out, my old exhaust mount had broke - causing the exhaust pipe to short out the rear wiring harness- burning the wires all the way back to the plug in connection- melting all the sensors associated. The FJ80 would run, but- the shifter would not shift without pushing the shifter over-ride button. But, the ECU fuse would pop as soon as you stuck one in. New harness and new sensors- no problem since.

Wiring checks out fine, although, I did have the same problem with my 2TZFZE Previa where an exhaust leak burned right through the O2 harness

I just bought denso O2s from rockauto.com. About $130 for the pair.

No $h!t??

I just paid that for the rear alone from Mr. T

It arrived at my shop today, but i won't get a chance to install it until tomorrow

 

[98 SNAKE EATER]

Installed a new rear O2 sensor this morning and she's good to go again

 

[johns94cruiser]

About 4 years ago, before I found out what a Land Cruiser was...I was driving mine at 70 mph in Georgia, left lane, tons of traffic...and everything shut off, threw it in neutral, squeezed between a couple of cars to the right and pulled off (no space to pull off into median, they installed those high tension wire medians).

Shorted O2 sensor. Someday I should replace the other one, but my gas mileage improved after it was unplugged.