Hi All,
I'm trying to install an overhead compass/temp sensor console in my 99 F150 XLT. The truck never had a console and I'm trying to understand all the signals I need to run up in the headliner to the circuit board. the plug has 12 positions but only the first 6 wires are populated. Here are the wire colors and positions and what I have discovered about them so far... (side note: i have the OEM repair manual and wiring diagrams books but cannot find this circuit yet. if someone knows the circuit number I would be most appreciative. I thought I found it on one random internet search (C945) but I don't see an entry for C945 on the index page. so either the 1999 f150 never had this option or I've got the wrong number. anyway, on to the wires I tested...
1 - White with a blue stripe - circuit main power (not sure if this should be constant 12v or switched 12v) (In a later post I discovered this is switched 12v or "hot in run")
2 - Black with a blue stripe - runs to the ground plane on the circuit board. (Main ground)
3 - gray with a black stripe - do not know what it does yet (in a later post i discovered this is the VSS signal)
4 - Blue with a red stripe - do not know what it does yet (in a later post i discovered this is the illumination signal)
5 - Blue with an orange stripe - The temp sensor had this wire so I connected the temp sensor wire here for the test (temp sensor output)
6 - Pink with a black stripe - The temp sensor had this wire so I connected the temp sensor wire here for the test (this also goes to the ground plane of the circuit board) (temp sensor ground)

What I have tried so far is to apply 12v to pin 1 and ground to pin 2. I also connected the temp sensor to the same colored wires of the harness. the result was that the unit powered up and only shows 71 degrees F, 22 degrees C, and NE on the compass. I rotated the unit but the direction never changes. I also hit the sensor with a hair drier but it never budged off 71 degrees. however if i disconnect the sensor it changes to "Ice/-40 degrees"

So my big unknown questions are these:
what do pins 3 and 4 do?
why would the compass and temp sensor not change when I heat up the sensor or rotate the circuit board.
do the other 2 wires (pin 3 and 4) have something to do with this inactivity?

Thanks in advance for any help
Peter

 

The 99 F150 didn't have that as an option.

What was the donor for the new module?

 

The donor truck was a 2001 or 2002 I believe. I thought it was going to be an easier install than its been so far. I ended up having to change out the sun visors since the way the free ends anchor to the roof is different. it was a pleasant surprise to discover that sun visors can just be muscled out of the rod they attach to. its just a long rod with a lot of friction holding them in place. now i know if they ever get squeaky i can just pull them out and add some lube. Also, the headliner was different enough around the seat belts that i cant use the donor trucks headliner. I'm going to have to cut my original headliner to make the overhead console fit. since my headliner is already out of the vehicle, ill just cut it to fit and then add the new fabric i already had planned for it.

I did finally find out the last two wires from my list above. Now the trick will be to find the best place to tap these wires to make a harness.

Shout out to user "SSCULLY" on a post they did that had the technical document i needed for this project. not sure how to link to that thread here but it was on 09-06-2011, 10:33 AM and ill attach the image below

1 - White with a blue stripe - circuit main power (switched 12v)
2 - Black with a blue stripe - Main ground
3 - gray with a black stripe - VSS or vehicle speed sensor
4 - Blue with a red stripe - Illumination
5 - Blue with an orange stripe - temp sensor output
6 - Pink with a black stripe - temp sensor ground

Question: For the 12v line going to the module for power, if the repair manual says "Hot in run" would you guess that it is switched with the key? or in other words it's only active when the truck is running?


Credit to SSCULLY for originally posting this. not sure how else to give credit.

 

Yes, that is what hot in run means.

 

Any thoughts on the behavior I saw on the module when I powered it up on the bench? the temperature was a rock solid 71f / 22c even when I used a hair drier on it and it only read north or north east no matter which way I rotated the board. Do you think the VSS needs to be doing its thing so the truck thinks its moving?

Update: I found that if I power the unit up pointing in a direction it will display that direction but wont change. I have seen it display all the directions now. I guess there is something to the VSS signal being active. will hopefully know more when the unit is in the truck.

Update to the Update: I've seen the unit change direction if I rotate the board now. It just takes an unpredictable amount of time to update the screen. sometimes its more than 10 seconds I guess it may update faster if the VSS was pulsing faster. In my case since I'm on the bench and not in the truck so that wire is not hooked to anything at the moment. The temperature also changes in this same slow unpredictable way.

 

I think it will work fine once it is in the truck.

I know on some of the vehicles I've driven with the compass and the temp, it is slow to update. Mostly the temperature seems to take forever.

On my F150, I just have the air intake temp showing on my SGII and that is enough to show the current outside temp for me. Only time it's wrong is when I've been sitting and there is some heat soak.

 

 

Direction change is detected by the magnetic lines of force on the cab top.
As the cab changes position the magnetic property that exist changes.
.Even after you get it installed the direction may not show correct if a procedure is not done according to the service manual.
After all a change in direction has to have a reference in relation to a position change on earth same as a hand compass.
The VSS signal keeps resetting the circuit so it can show a new direction in a short amount of time.
My 90 Lincoln uses the same method.

 

Thanks for the wiring info. I bought a rear view with the auto dimming and homelink from a 2010 Nissan to put in my 04 Heritage and needed the hot and ground wires. I would have guessed the red and black with blue stripe to be hot and ground and would have been wrong! All wired up and ready to program nd will be nice to have auto dimming for bright lights from behind.

 

My wifes car has auto dimming and I wish i had that in my truck. Neat idea to use some other brand mirror that has the features you want. I tried to use some cheap aftermarket junk that attaches over the factory mirror and was disappointed with all the vibration. Glad the wire colors helped, I know how frustrating it can be when you see odd factory wire colors and have no idea what to hook up to.

 

I actually got the idea from another F150 forum! My last two cars have had that auto dimming and Homelink in mirrors so when I picked up this truck last year, after driving on the highway one night said i gotta fix this! Cost me $25 on Ebay, only downside is mirror isn't quite as wide as original.

I think another guy got a Lincoln or Mercury sun visor which may had the homelink built in to put in his older F150. I'm always nervous leaving garage door openers in cars in case we forget to lock car. My wife has an 11 Regal with no homelink but can't put one in because of the damn Onstar, Guess GM didn't want to pay fees to put in vehicles.

 

Ford had auto dimming mirror in later models of the 10th gen. But its a pretty rare option, most likely to be seen in a King Ranch, or Navigator

 

also on Lariats.. I use the mirror 12v to tap in a usb hardwire for my mirror cam. My windows are soo dark my oe mirror NEVER "dimmed"...lol