Outside air temp display is blank

New member here. Looking forward to learning from this forum.

My outside air temperature display is now blank upon restoring from an aftermarket radio install. 07 Tundra Limited, crew cab. No I didn’t disconnect the battery. The AC light flashes until I push to acknowledge it. Otherwise, AC and heat still work. I checked all fuses, all wiring. There is no voltage at the temperature element. Did I fry the AC Amplifier? If I knew the circuit I could do a little more troubleshooting. The AC amplifier is a 88650-0C070. Thanks in advance!

 

My ac light was flashing in my 4Runner the other day- it was a bad ac relay. Not sure how that would correlate to the temperature reading, probably doesn’t. You might have two problems or maybe the temp blanks when there is an ac problem as well as the ac light flashing.

Edit... temp sensor wouldn’t really show voltage. Disconnect and check resistance to see if it’s good.

 

I will check the resistance on the temp element. I found a drawing online that showed there was a few volts to the element. I check both leads to ground and nothing that’s why I think there is a signal issue. I’m not sure if the outside temperature is part of the logic for the AC Amplifier. Anyone?

 

I would try disconnecting the battery for 30 minutes before doing any additional diagnosing. Wiring diagram may or may not help you.

 

I tried the battery disconnect for 10 minutes. I will go longer. Thanks for the drawing.

 

Hit the wiring diagram link in my signature and you can pull down the full EWDs for your model year, which will be useful for other things.

 

The drawings were exactly what I needed. Thank-you! My troubleshooting narrowed the issue down to what appears to be an open between AJ3 connector and the temperature sensor. I did a hand over hand of the wiring and didn’t find any corroded or faulty wiring. I tested the element and its resistance is ~1.5K Ohms and varies with heat (measured disconnected of course). Not sure where to go next other than running a fresh wire from AJ3 to the element?

 

Battery was disconnected overnight. Display still out.

 

Did you try a jumper wire between the connectors you identified?

 

Not yet. That is my next step. I will update after I test this.

 

Jumper wire worked! Now I can run a wire and be done with this and relax about it. I wish I knew where the open is to inspect and repair. Maybe it will roar it’s ugly head with additional faults but oh well. Thanks all for the help.

 

Jumper wire worked! Now I can run a wire and be done with this and relax about it. I wish I knew where the open is to inspect and repair. Maybe it will roar it’s ugly head with additional faults but oh well. Thanks all for the help.

 

Great! Good job and thanks for the update.

 

^ This is what this forum is about.
Helping each other out.....

Glad you got it fixed..

Welcome to the forum from Dallas....

 

Where did you find sensor AJ3 and A15?

 

AJ3 is a junction connector for the wiring. Generally for when wiring comes in from the engine bay to the cab, it passes through a connector.

A15 is the connector plug for the temp sensor. It is on the front grill area drivers side I think.

The sensor reads the exterior temp from the grill area, the data is passed along to the wiring into the cab of the truck to the AC ecu behind the glove box. The AC ecu processes the temp signal and sends it out to be displayed.

The original posted is saying the wire from one side of the sensor of the grill to the firewall of the truck had a bad connection. The wiring on the inside from the firewall to the AC ecu was good, he had a break in the section in the engine bay.

 

So, I just need to trace the wire from A15 to the firewall and then place a jumper back to A15?

 

That is what he had to do to fix his, If I was you I would be looking over the whole circuit to see where your problem is. Techstream can read trouble codes out of the AC Ecu, could be very helpful in this situation.