Anyway to change the factory default preheat setting?

Due to an accident I got a lot of metal in my body and currently preheat my IC car to about 80 before I get into it. I read somewhere the factory default setting is like 77F, can the dealer or someone change the factory set preheat temperature?
I'm sure there must be someway to tweek this?

And to double check the seats preheat too right?

Nope, it is hard programmed and not adjustable.

mrradon said:

Due to an accident I got a lot of metal in my body and currently preheat my IC car to about 80 before I get into it. I read somewhere the factory default setting is like 77F, can the dealer or someone change the factory set preheat temperature?

Click to expand...

mrradon said:

And to double check the seats preheat too right?

Click to expand...

Yes, if they are in the on position.

mrradon said:

Due to an accident I got a lot of metal in my body and currently preheat my IC car to about 80 before I get into it. I read somewhere the factory default setting is like 77F, can the dealer or someone change the factory set preheat temperature?
I'm sure there must be someway to tweek this?

And to double check the seats preheat too right?

Click to expand...

The factory setting is 77F, but attacking from the other angle -- there must be a sensor (or sensors) that the vehicle uses to determine the cabin temperature. Typically such a sensor reports by means of a resistance value. So it may be possible to "fool" the car into thinking that 80F is really 77F, for example...

Yep, it is behind that little grill to the right of the steering wheel. You could trick it that way but would likely want to put a switch on it so you could return it to normal for regular climate control operation. Some have talked of doing just that - but in the opposite direction - to defeat the heater operation when desired by making it think the car is actually warmer than it really is...

Nubo said:

The factory setting is 77F, but attacking from the other angle -- there must be a sensor (or sensors) that the vehicle uses to determine the cabin temperature. Typically such a sensor reports by means of a resistance value. So it may be possible to "fool" the car into thinking that 80F is really 77F, for example...

Click to expand...

Thanks for the advice. Perfect solution is to remove the thermistor and measure the characteristics across the temperature range and recalibrate it to sense lower temps than actual. Awesome idea guys!

I spent the $20 and got all the Service Manuals, and all the Service bulitines and all the training courses...WOW - well worth the $20!

So I found the graph of the In-Vehicle Sensor's resistance vs temp (its a thermistor).
From that I did a quick regression and calculated the resistance between the data points. (HAC-13, JPIIA1862GB)

So to trick the sensor to get the cabin temp from 77F to 82F just add a 211 ohm resistor! I'm going to wire in a two pole switch. I can flip between 77F and 82F. Will update when I get the car and test it.

How much resistance to add to get to the desired temp.
85 add 338ohms
84 add 296ohms
83 add 253ohms
82 add 211ohms
81 add 169ohms
80 add 127ohms
79 add 84ohms
78 add 42ohms

What the sensor reads at a particular temp. Data points are at 86, 77, 68, 50. The rest are interpolated from the sensor preformance curve.
F KW
86 1.81
85 1.85
84 1.89
83 1.94
82 1.98
81 2.02
80 2.06
79 2.11
78 2.15
77 2.19
76 2.24
75 2.29
74 2.34
73 2.39
72 2.45
71 2.50
70 2.55
69 2.60
68 2.65
67 2.72
66 2.80
65 2.87
64 2.95
63 3.02
62 3.10
61 3.17

If you are going to all the work anyway, I'd put in a dpdt switch with a center off position wired so that you can raise it or lower it. Lowering it (making it think it is warmer than it actually is) would allow you to prevent the heater from coming on.

mrradon said:

So to trick the sensor to get the cabin temp from 77F to 82F just add a 211 ohm resistor! I'm going to wire in a two pole switch. I can flip between 77F and 82F. Will update when I get the car and test it.

Click to expand...