Fixed: Turning on the AC blows IG1 #2 fuse

Todays update:

Turns out the violet wire running to the ac clutch also supply’s power to the Compressor Pick Up Sensor (#88346-04010). I now believe this may be where my short or excessive voltage is coming from.

When the violet wire bundle is plugged into the sensor I get full voltage and the test light lights when testing the violet wire to battery. With the sensor unplugged I get no voltage or light. I no longer think I have a shorted wire in the bundle. Glad I didn’t cut wires, I was close a few times.

With the MG CLT plugged back in and all connections back to normal, except the plug to the sensor I don’t blow the IG1 #2 fuse. AC kicks in for about 3 seconds then the AC light flashes as expected sense the sensor isn’t sending data.

I get continuity across all 3 pins of the sensor to each other from 1.9-4,9. Attempted to test it using these directions, which proved impossible. When I finally got it setup and hooked to the battery, the sensor started smoking. Not sure if this was because of my method or because it was shorted internally.

Either way, it seems like my only next option will be to buy a new sensor, right? I don’t think I have any more options to test.

 

Looks like you found the smoking gun (sensor).
These can be hard to get of as last I heard they were back ordered. Let me see If I can locate a source.

 

This is the part # Toyota 88346-04010 Sensor, Compressor Pick Up

2005-2016 Toyota Tacoma 8834604010

https://parts.olathetoyota.com/oem-parts/toyota-sensor-compressor-pick-up-8834604010

Looks real pricey at the dealership. $135.33


and

https://autoparts.courtesytoyota.com/products/product/sensor-compressor-p-8834604010

$162.40

 

So that sensor is inline to power the clutch? Its obviously not a pressure sensor. What does it sense? Temp?

 

I ordered it locally for pickup in hopes to get it before the weekend. $142 after tax. Hopefully it is actually available.

Within the Compressor bracket harness, the orange wire (was violet before the harness) splits off before the sensor plug to power the clutch. Oddly it looks like it is a soldered connection wrapped with tape. I’ll post a photo before I put it all back together. The sensor is mounted to the compressor.

The pick up sensor is a speed sensor to report back to the AC Amplifier.

 

The Lock Sensor reports A/C Compressor RPM to the A/C Amplifier, the Amplifier uses this in conjunction with Engine RPM to determine if the Compressor is rotating at the correct speed.
If the A/C Amplifier sees no signal or an incorrect signal from the Lock Sensor it assumes the compressor has stopped turning and turns off the MG CLT relay to prevent damage to the drive belt.

 

Fixed:

The compressor pickup sensor was in stock so I was able to pick it up and install today. The new sensor fixed the issue.

The new sensor had no continuity from pin to pin. The old one had continuity between each pin to the other.

One 8mm bolt holds the sensor in place and it was easy to take out. It was a nightmare to put back in.

Here is the sensor.


Here is the factory spliced wire coming from the compressor bracket wire harness that provides power to the sensor and clutch. This comes directly off the violet wire coming from the MG CLT relay.

 

Good Job! Thanks for the update!