Anyone out there with electrical wisdom?

[fyrfytr33]

So I have found this site very informative and it has helped with most of my issues. So first I want to thank everyone here. So here is my issue, I have a 1998 K2500 GMC Sierra SLT, 7.4L Ext cab 2 door. The truck has most everything I could want but right away I found the rearview mirror didn't have the Temp/Compass option. So I bought one, installed it, got a wiring harness from a Suburban, and wired it up. Works fine but the temp is reading about ten degrees warmer than actual ambient air temp. So with my limited knowledge of electronics I thought I would ask, is it possible to put a resistor inline to bring the temp display more inline with the actual temp? If so how do I go about figuring out how much resistance I need to change ten degrees? It seems like it would work without very much hassle but I need some advice. I mounted the sensor behind and below the drivers side parking light. I used the original plugs and wires where I could and soldered and covered everything with heat shrink, split loom or electrical tape. I also added the Home-link panel to the OH console, I'm not sure where to pick up the signal to dim the lights when the headlights are on. I thought I found the correct terminal on the convenience center but it works with the dimmer switch for the dash lights not the same as the dim function for the radio display. Thank you for any help.

 

[1997chevydriver]

For one the sensor should be mounted in the path of airflow, on the center pillar where the horn is mounted on the core support is a good spot.

Where you have it mounted is in a "stale air" zone.

 

[fyrfytr33]

I don't mean to seem rude, but I don't see how it matters if it has air sitting or moving around it. It works by transmitting the resistance to the chip that is programed to display a number based on what the resistance is. If the truck were to sit in a garage not running the sensor will read the temp of the garage. Unless they programmed it to figure wind chill from the air moving past the sensor it should read correct if it is in the airstream or in a location with still air, assuming it is not in still air that is heated. That is why I placed it away from the radiator. I did read somewhere it uses some pre-programmed time periods to try and determine if the radiator is still warm or not. It tries to avoid giving a false reading by showing the last temp it read if the truck is started within two hours of the time it was turned off. Still I'm just wondering if anyone can steer me to a solution with a resistor to make it read more accurately. I do have another sensor I may try comparing the resistance and see if they match.

 

[1997chevydriver]

It figures in the air flow speeds based on the vss.

Your other option is try a handful of sensors and pick the closest one

 

[magimerlin]

Why try to invent the wheel? It's a small sensor, just put it on the center support by the horn where it was mounted with the factory option setup and be done with it. Not trying to sound rude but the rule of KISS applies here. There is no timer delay, it doesn't compute with speed changes. It's a simple temp probe. I've installed these a dozen times now and never had an issue installing in factory location.


Sent from what use to be a great country.

 

[fyrfytr33]

I'll try moving it and see if it helps. I do believe in the KISS principle. I was trying to avoid moving it since I soldered all the connections and cut the wire to length. I should of thought it out better and left more slack. Maybe I can come up with a weather tight plug and use it this time. I have a second sensor I'll try it also and see if the temp gets closer. I appreciate everyone's opinions. Thank you.

 

[1997chevydriver]

I'll try moving it and see if it helps. I do believe in the KISS principle. I was trying to avoid moving it since I soldered all the connections and cut the wire to length. I should of thought it out better and left more slack. Maybe I can come up with a weather tight plug and use it this time. I have a second sensor I'll try it also and see if the temp gets closer. I appreciate everyone's opinions. Thank you.

Being in the flow of air helps and I had to try 2 or 3 before our got within a few degrees

 

[fyrfytr33]

OK, I moved the sensor and it seems closer but still reads a little high, 8-9 degrees. I think I'll try another sensor. You have good points and I think the resister idea was overkill. Sometimes my OCD kicks in and I go for perfection when close is good enough. By the way I cringe when I hear the words "close/good enough".