wiring diagram

does anyone have a wiring diagram for the climate control harness for a second gen?

 

Here you go.

 

Hi Super_white,

Thanks for the diagram. OP is a few days ahead of me in posting the request.

2 questions:

1) Do you know where I can find the accompanying symbol legend for the wiring diagram? I'm good with schematics (45 yr EE), just not some of the automotive symbols.

2) maybe wrong place to post - I'm troubleshooting the A/C on my '12 Taco. Could use some ideas.
The A/C light comes on on the dash. No clutch engagement. The MGC relay itself tests sat, but the solenoid is not being driven to close. +B on one side, low V on the other, not 0V. I can jump the MGC power at the relay location and the clutch engages and I can hear refrigerant. (Didn't leave it shorted long enough to see if air got cold.)
If I'm interpreting the schematic correctly, the fact that the A/C indicator light is on indicates that the A/C amplifier thinks everything is good. For the A/C amplifier to engage the compressor, what conditions need to hold? Other troubleshooting ideas?

Thanks,
Eric

 

If the A/C light comes on and isn't flashing but the clutch doesn't engage then conditions aren't correct.

It has to see:
The Dual Pressure Switch closed (greater than 25 psi and less than 425 psi of refrigerant pressure in the system).

Evaporator Thermistor in a valid range.

Ambient Temp Sensor in a valid range (09+)

A/C enable signal from the ECM.

RPM signal from the ECM.


First thing I would do is hook gauges up to it and verify there is refrigerant in the system.

 

Hi Dm93,

Exactly the kind of info I was looking for. Thanks so much.

It does not appear that the A/C amp is even trying to close the relay, so that suggests bad initial input conditions - pressure switches, temps, A/C enable from ECM. (I'd expect a RPM mismatch to occur after the clutch engaged.)

Where would you recommend probing the signals you mention? I've always found it frustrating that there are no E-points/Test-points built into vehicle wiring. If I understand yours and other's posts, the A/C amplifier is high on the wall up behind the glove box - a pretty ugly place to try and probe.

(I don't have the gauges necessary to check system pressures. Plus, I don't relish the idea of attaching hoses and potentially losing refrigerant. Was hoping to let the switches tell me if I was within limits.)

I have not checked IG1 or IG1_no2. Wouldn't I have all kinds of other problems/indications if either of those was out?

btw - I see you've been answering these A/C questions for at least a decade. Thanks!

Eric

 

Quickest and easiest thing to do if your unsure weather or not it has refrigerant in it and don't want to hook gauges up is to unplug the Dual Pressure Switch on the liquid line near the right (passenger) side of the radiator and briefly jump the terminals with a small paperclip with the engine running to see if the clutch engages, if it does then odds are the refrigerant has leaked out.

 

You read my mind. Exactly what I was going to try. (And, you saved me looking up where to find the switch.) If shorting results in the clutch engaging it's either lack of refrigerant or a bad switch. Either way I'll have to run it by mechanic as I can't purge and recharge it myself.

Thanks again.

 

Sho' nuff. I put an ohmmeter on the switch. Open. Shorted the cable. Clutch engages. Can hear some refrigerant, but no cold air. (Shut down quickly to protect seals.)
I'll give you the final diagnosis once my mechanic puts it on the gauges, but the good news is it seems to be neither the A/C amp nor the compressor.
Thanks again,
Eric

 

Hopefully they can find the leak and it's an easy fix, being a 12 it should have dye in it from the factory.

 

I'd give it about a 92.

My mechanic said there was no refrigerant in the system. Uh oh. But he pulled a vacuum and it held for 20 minutes or so. Encouraging but not a slam dunk. He then refilled the system including dye. No apparent pressure loss. No visible dye. Cool air. Lookin' good. Drove it in the 100+ heat today. Nice and cold. HOWEVER, on two or three occasions while idling, it tripped off. (Loss of cool air. A/C lamp blinking.) Once moving, a quick cycle of the button cleared the problem. Belt slippage? My serpentine belt has looked better. I'll probably replace it.

Regardless, I'm driving around cool and comfy in this hideous "heat dome" weather. Thanks for the advice.

Eric

 

Might give it a look over for dye after a few days and see if anything shows up.

Possible, the flashing A/C light indicates the A/C Amplifier isn't getting the correct signal from the Lock Sensor on the compressor.
Intermittent ones can be pretty difficult to diagnose.

Possible causes are:
Open or shorted wire(s) in the lock sensor circuit
Bad lock sensor
Failing MG CLT Relay
Internal problem in the compressor
Open or shorted wire(s) to the MG CLT relay
Open in the wire from the MG CLT relay to the compressor
Failed compressor clutch
Belt slipping
Failed A/C amplifier

 

Dm93,

That's a whole lotta causes. As the failures were peculiar to the state of the truck - stationary and idling, I'd tend to rule things like bad wires, relays, amplifier, etc. as unlikely. High compressor load, low RPM on a stinking hot day. Sounds like something internal to the compressor or slipping belt. I'm going with the belt as the compressor related causes are too expensive to contemplate. ;-)

Thanks again for all the help. You've now taught me more about automotive A/C than I care to know.

Eric

 

If all else fail, You have 2 other AC buttons to try.
One on the Drivers door, the other on the passengers.
They work better once you get 45+ mph.......

 

Yep. Many of my cars have had CramAir55 air conditioning.