Remote start automatically set heat and blower
Printed From: the12volt.comForum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=142016
Printed Date: May 14, 2025 at 4:03 AM
Topic: Remote start automatically set heat and blower
Posted By: mbroughton02
Subject: Remote start automatically set heat and blower
Date Posted: November 13, 2016 at 9:46 PM
Hi,
I have a Viper remote start in a 2007 Toyota Tacoma. I plan to connect the Aux 1 output to turn on the blower to high, and the temperature control to full hot.
According to the truck's factory service manual, the temperature setting knob is basically a potentiometer. is it puts +12v on a wire for full cold, 0v for full hot, +6v would be warm, etc. See attached diagram from the service manual. I'll refer to that wire as the temp setting wire.
So I have a SPDT relay. I set it up so that it triggers with the Aux 1. It interrupts the temp setting wire. Pin 30 has the potentiometer output. 85 has the viper's aux 1 output. 86 has +12v ignition power. 87 has nothing. 87a has the temp setting wire to under the dash, apparently to an amplifier then an air mix servo.
My "theory of operation" is that under normal (non-remote start) conditions, The temp is set by the potentiometer, and that voltage goes straight through the relay because 87a is a NC contact. When the truck is remote started and Aux 1 is triggered, the relay turns on and now whatever voltage is on the wire from the potentiometer is diverted to 87, which goes nowhere. This means the temp setting wire to under the dash should have 0v on it, which should signal full heat.
Here's the problem. When the temp setting wire to under the dash is disconnected by the relay, it suddenly has 6v on it. So the truck blows warm, not hot, air. So, somehow the truck's potentiometer manages to put 0v on that wire, without actually opening the circuit. Because when I open the circuit, I get 6v.
How can I replicate that so that the viper can set the temp to full heat?
I did get the blower motor working on Aux 1. I used two relays. One relay grounds the wire that sets the blower motor to high, and one relay puts 12v on the wire that triggers the truck's blower motor relay.
I have a Viper remote start in a 2007 Toyota Tacoma. I plan to connect the Aux 1 output to turn on the blower to high, and the temperature control to full hot.
According to the truck's factory service manual, the temperature setting knob is basically a potentiometer. is it puts +12v on a wire for full cold, 0v for full hot, +6v would be warm, etc. See attached diagram from the service manual. I'll refer to that wire as the temp setting wire.
So I have a SPDT relay. I set it up so that it triggers with the Aux 1. It interrupts the temp setting wire. Pin 30 has the potentiometer output. 85 has the viper's aux 1 output. 86 has +12v ignition power. 87 has nothing. 87a has the temp setting wire to under the dash, apparently to an amplifier then an air mix servo.
My "theory of operation" is that under normal (non-remote start) conditions, The temp is set by the potentiometer, and that voltage goes straight through the relay because 87a is a NC contact. When the truck is remote started and Aux 1 is triggered, the relay turns on and now whatever voltage is on the wire from the potentiometer is diverted to 87, which goes nowhere. This means the temp setting wire to under the dash should have 0v on it, which should signal full heat.
Here's the problem. When the temp setting wire to under the dash is disconnected by the relay, it suddenly has 6v on it. So the truck blows warm, not hot, air. So, somehow the truck's potentiometer manages to put 0v on that wire, without actually opening the circuit. Because when I open the circuit, I get 6v.
How can I replicate that so that the viper can set the temp to full heat?
I did get the blower motor working on Aux 1. I used two relays. One relay grounds the wire that sets the blower motor to high, and one relay puts 12v on the wire that triggers the truck's blower motor relay.
Replies:
Posted By: i am an idiot
Date Posted: November 14, 2016 at 10:01 AM
Posted By: mbroughton02
Date Posted: November 14, 2016 at 2:44 PM
Posted By: mbroughton02
Date Posted: November 15, 2016 at 9:42 PM