What happens when you mix a computer geek with automotive electronics

[FMCoug]

So my truck has a bad Barometric Pressure Sensor. This sensor basically measures altitude via barometric pressure so the computer can provide the appropriate mix of fuel and air, adjust injector timing, glow plug on time, etc. The way it does this is by translating the pressure into voltage between 0 and 4.6 volts. 4.6 is sea level. 2.6 is 10000 ft. Anyway, mine was not working so it just read open (0 volts), causing issues with the truck.

Ford wants $155 for the part. I found it aftermarket for as low as $80 but that is a lot of money regardless. Plus I couldn't find one locally for less than $115.

Then I got to thinking. The connector for the sensor has 3 wires. One that is the PCM (engine computer) supplying 5 volts to power the sensor. The other 2 are ground and signal for the voltage it sends back. My old sensor had been working intermittently and I knew it had been reading 3.7 volts. So I figured I could jumper the 5V line and the signal line with a resistor to trick the computer into thinking the sensor is working.

The result? My redneck barometric pressure sensor. Guess I'll have to take some different valued resistors with me if I take the truck to CA or other lower eleveation places.

[FN Phat]

You are incredible cheap when it comes to most things. I wouldn't bat an eye on an automotive part that cost $80, as long as I could install it myself and it corrected my problem. I am not hating, I just wish that I had enough confidence in my own abilities to come to a remedy (ie, jury rigged).

Good luck with the fix.

[FMCoug]

You are incredible cheap when it comes to most things. I wouldn't bat an eye on an automotive part that cost $80, as long as I could install it myself and it corrected my problem. I am not hating, I just wish that I had enough confidence in my own abilities to come to a remedy (ie, jury rigged).

Good luck with the fix.

Oh I will likely order it. I just wanted to make sure that was actually the issue before I order something online, wait for it, have to send it back and pay the shipping, etc.

Also it's a matter of what you know. Lots of guys would weld up a bracket for stuff, get a machine shop to do some sort of custom part, etc. That's stuff I wouldn't do. But electronics I know.

[Uncle Ted]

The result? My redneck barometric pressure sensor. Guess I'll have to take some different valued resistors with me if I take the truck to CA or other lower eleveation places.

What about just using a variable resistor? If you knew the specs on the barometric pressure sensor you could figure out what the resistance setting should be for various altitudes so you can dial them up.

[FN Phat]

Oh I will likely order it. I just wanted to make sure that was actually the issue before I order something online, wait for it, have to send it back and pay the shipping, etc.

Also it's a matter of what you know. Lots of guys would weld up a bracket for stuff, get a machine shop to do some sort of custom part, etc. That's stuff I wouldn't do. But electronics I know.

I understand. I just hope that I can do those things one day. I have a dream of building a classic truck (I really dig F100s from the 40s-late 60s, chop the top, slam it on the ground with airbags and roll on 20s in the front and 22s in the rear) one day. I have a lot to learn and a lot of money to find.

[FMCoug]

What about just using a variable resistor? If you knew the specs on the barometric pressure sensor you could figure out what the resistance setting should be for various altitudes so you can dial them up.

Yeah I thought about that. For that matter, I bet I could find a chip that does barometric pressure and design my own circuit for a lot less than $80. But I'll probably just replace the sensor eventually.

This really was just what I could cobble together with what I had on hand.