2007 Tacoma A/C Blinking Light

Hey all, have the lovely blinking light when I push A/C. On a rare occasion it will work and the compressor engages, this is not the norm. Jumping the relay engages the clutch no problem. Pin 1 on the relay(I believe this is grounded to engage by the AC amp), is always OL, never get continuity to ground when I test. Engine RPM will raise slightly when the A/C button is pressed, but after 2-3 seconds, it calms down and the light start blinking. The compressor never engages during this time. I have replaced the AC amplifier, pressure switch under the hood is reading 0ohms, so I believe it is good. Which Im pretty sure puts me at a wiring issue between the amp and relay. Is there a way to get to the wiring harness of the AC amplifier(remove the passenger side dash?) or would the entire dash need to be removed? There isn't much room to work in there. The only diagram I find also has a notation on the Grn "trigger" wire 31[IA1], Im assuming this is a connector/junction at some point. Just don't know how to find it.

Thanks!

 

Do you have a test light?

If so we can narrow this down pretty quick, test light connected to battery Ground check for power on Pin 2 & 5 of the MG CLT Relay with the key on.
Then test light connected to battery Positive check Pin 3, it should light up if the wire is continuous to the clutch coil and the coil windings are good.

If that all tests good then with the light still connected to battery Positive start the truck and have an assistant hit the A/C button while you hold the light on Pin 1 of the MG CLT Relay, it should light up briefly until the light starts flashing.

 

Thank you for the quick reply! I do not have a test light, but with multimeter I get 13V between ground and Pin 2, Pin5. 13v between Positive and Pin 3. When having someone press the A/C button, multimeter connected to Pin 1 and batt ground, I read OL the entire time. Let me know if I should be testing this some other way.

This is one of the threads I have worked through, https://www.tacomaworld.com/threads/ac-clutch-not-engaging.723464/page-2. It is leading me to believe either the new AC amp is bad, or there is a wiring issue.


Thanks

 

Continuity/resistance testing isn't a good way to check circuit integrity and it doesn't really work at all on live circuits.

You could set your meter to volts DC and check accross pins 1 and 2 while pushing the A/C button and see if you read battery voltage momentarily.

 

Ok, I tried that, reads 0.00v with no fluctuation.

 

Ok and Pin 2 of the relay has power with the key on?

 

Between pin 2 and batt neg reads 13V, yes.

Just double checked since you asked with key on, not running. Key on I read 11.9v, running 13v.

 

Ok then you will need to go to the A/C Amplifier behind the glovebox.

Pin 21 (Green) is MG CLT Relay control, you will probably need a needle or paperclip to use as a backprobe. Check between that pin and a power source while you get someone to push the A/C button.

 

Pin 2 (Black/Yellow) of the blower motor connector would probably be the closest and most convenient power source in that area.

 

Ok, well, I get 13v(vehicle running) for about 2 seconds between pin 21(dark green wire) and the blower positive. So amplifier is good Im guessing? Signal is just not making it to the relay/relay plug.

Thanks for all the help

 

So we have a broken wire, we can split the circuit in half at connector IA1 behind the left kick panel, Pin 31 (Green) is the MG CLT Relay control wire.
Plug the relay in and chack between IA1 Pin 31 (Green) and a known good ground with the key on. If you have power there your break is in the interior harness, if not it's broken on the engine harness side.

 

Sorry, took me awhile. Could not find a way to count pins on that connector that put 31 on a grn wire. Probably just my misunderstanding of how they do that. Ended up testing every solid grn wire to ground, and then disconnecting the A/C relay to see if it went to 0, believe I found the correct one on the top left of the connector. 13V to ground with relay connected, pull the relay, it goes to 0v. That being said, it would point to a broken wire behind the dash correct?(not surprising, I live in the country and mice are everywhere. Found a couple other wires that need to be fixed in this process). Im guessing there is not, but is there a fairly simple way to access that harness?

Thanks!

 

Ah you should have asked, I have that too as well as a full pinout of that connector and every other junction & harness joining connector for 05-08.
https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042160

I was thinking it would be broken outside but behind the dash is tough, there's not alot of access to harnesses back there aside from what you can get to by pulling panels. Otherwise you would likley have remove quite a bit of the dash if it's back there.

 

I appreciate that, will go double check now. I figured it wouldn't be a pleasant task if it was behind the dash. Since that seems to be the only issue, Im toying with the idea of just splicing in a new wire from the controller to the IA1 connector. Its a paid off truck with 370K miles(my daily driver, and I work from home), not sure its worth all the hassle to pull all the dash. I live in Texas, so A/C would be nice to have again though...

Double checked, thats the wire I found testing. So it is behind the dash.

 

Well if that's the only wire that's compromised it certainly wouldn't hurt to do that as a "temporary" fix.

 

"temporary" meaning until the truck finally dies and I buy a new one. Although Im not entirely sure a Tacoma can die... I really appreciate the help and wiring diagrams! Thank you!

 

That's why I put temporary in quotes because those temporary fixes tend to become "permanent" if they work.

And I hear ya about not having A/C in Texas, it's been ridiculous here and it's not even legit summer for us yet.

 

Hasn't been to bad up here in North Texas, bit on the soggy side, maybe a little warm here and there. Real heat will be here soon. Again, I appreciate the assistance!

 

It's been hell here in south central Texas, dew points in the upper 70s to mid 80s and temps in the upper 90s with no rain to speak of.

 

Ran a new wire for grn, I now have A/C. Been 2 yrs I think, I really appreciate your help!