Need someone with electrical knowledge to confirm this....

bobc · 03-03-2005, 09:22 PM

I rarely ever switch from fresh air to recirculated cabin air. For the few times that I do, I can easily use the MFD.

I was thinking that I could free up the recirc switch on the steering wheel to serve as a mute switch for the radio since there's the external volume control for the radio and I could just tap into that.

But, after looking at the wiring diagrams, it looks like the recirc switch is not a simple on/off switch and is part of a more complex/combination switch for the air conditioner in general. But, what do I know, I can't read electrical plans... Is the latter true or can I tap into this and use this switch as a simple on/off for the volume control??

Thanx,

-bob

jeepien · 03-03-2005, 10:07 PM

To turn the radio off from the steering wheel, press the Mode switch and hold for two seconds.

brosnan · 03-04-2005, 02:48 AM

The RECIRC switch is connected to the wire labelled AC1 which goes to center terminal block post 5B-14. When you press the RECIRC switch you'll find 2.57V on wire AC1 . When not pressing, you'll find 4.83V. However, 3 other switches share this line and use different series resistor values to get 3 other voltages (3.68V if you press "INFO", 1.06V if you press "DEF-REAR" and 0V if you press "DEF-FRONT"). So if you really want to avoid the 2 second delay of the MODE switch you could build a circuit which detects voltage near 2.57V and then mutes the audio, but it would be a lot of work.

brosnan · 03-04-2005, 02:59 AM

The white wire on the large connector on the NAV ECU is a mute output. There's probably a way to add a mute switch to pretend the NAV ECU just asked for the mute condition.

bobc · 03-04-2005, 11:18 AM

Mike,

Thanks for the reply and all the info! As I look at the diagram while reading your explanation, that all makes sense. I couldn't figure out how 6 controls could operate off of just 3 wires, but I can understand that it's done by changing the voltage...

Yeah, it would be too much work to re-tool this...

BTW, I don't have the NAV option..

Thanks again,

-bob

DanMan32 · 03-04-2005, 02:50 PM

Yes, many of the controls are multiplexed by using a resistor network. Multistep digital, got to love it.
Cruise control stalk also uses this arangement, making it harder for Coastal to develop their EV mod to use the cancel switch.
Radio is a third.

03-03-2005, 09:22 PM	#1
bobc Senior Member Join Date: Jan 2005 Location: Durham, NH Posts: 360 My Car: Model: Package: Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	Need someone with electrical knowledge to confirm this.... I rarely ever switch from fresh air to recirculated cabin air. For the few times that I do, I can easily use the MFD. I was thinking that I could free up the recirc switch on the steering wheel to serve as a mute switch for the radio since there's the external volume control for the radio and I could just tap into that. But, after looking at the wiring diagrams, it looks like the recirc switch is not a simple on/off switch and is part of a more complex/combination switch for the air conditioner in general. But, what do I know, I can't read electrical plans... Is the latter true or can I tap into this and use this switch as a simple on/off for the volume control?? Thanx, -bob

03-04-2005, 02:48 AM	#3
brosnan Senior Member Join Date: May 2004 Location: Silicon Valley Posts: 159 My Car: 2010 Prius Model: IV Package: Navigation Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: Need someone with electrical knowledge to confirm this.. The RECIRC switch is connected to the wire labelled AC1 which goes to center terminal block post 5B-14. When you press the RECIRC switch you'll find 2.57V on wire AC1 . When not pressing, you'll find 4.83V. However, 3 other switches share this line and use different series resistor values to get 3 other voltages (3.68V if you press "INFO", 1.06V if you press "DEF-REAR" and 0V if you press "DEF-FRONT"). So if you really want to avoid the 2 second delay of the MODE switch you could build a circuit which detects voltage near 2.57V and then mutes the audio, but it would be a lot of work. __________________ Mike Brosnan 2010 IV + Nav +AutoNavLockDefeat Was Silver 2004 #9 +EV +AutoNavLockDefeat +AutoPhoneLockDefeat -Beeps +UnlockAllDoors ;

03-04-2005, 11:18 AM	#5
bobc Senior Member Join Date: Jan 2005 Location: Durham, NH Posts: 360 My Car: Model: Package: Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	Re: Need someone with electrical knowledge to confirm this.. Mike, Thanks for the reply and all the info! As I look at the diagram while reading your explanation, that all makes sense. I couldn't figure out how 6 controls could operate off of just 3 wires, but I can understand that it's done by changing the voltage... Yeah, it would be too much work to re-tool this... BTW, I don't have the NAV option.. Thanks again, -bob

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03-03-2005, 10:07 PM	#2
jeepien Join Date: Jan 2005 Location: New Jersey Posts: 165 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	To turn the radio off from the steering wheel, press the Mode switch and hold for two seconds.

03-04-2005, 02:59 AM	#4
brosnan Senior Member Join Date: May 2004 Location: Silicon Valley Posts: 159 My Car: 2010 Prius Model: IV Package: Navigation Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	The white wire on the large connector on the NAV ECU is a mute output. There's probably a way to add a mute switch to pretend the NAV ECU just asked for the mute condition.

03-04-2005, 02:50 PM	#6
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Yes, many of the controls are multiplexed by using a resistor network. Multistep digital, got to love it. Cruise control stalk also uses this arangement, making it harder for Coastal to develop their EV mod to use the cancel switch. Radio is a third.