: 2000 STS MAP sensor voltage high?



caddydaddy
03-13-06, 03:22 PM
My STS keeps blowing MAP sensors, and I can't figure out why! I know it has blown when I floor it and it bogs. It will set a code for high MAP voltage, but doesn't light the SES light. It has blown 3 times in the 3 years I have owned the car. Any ideas as to what is causing this? MAP sensors aren't cheap to replace! :eek:

eldorado1
03-13-06, 04:34 PM
If you have a factory service manual, check into the conditions required for your MAP sensor code to be set. It's possible that your MAP sensor is fine, but the TPS is bad. If the computer sees a large change in throttle without a corresponding change in vacuum, it will set a code. That can happen if the MAP is bad (you floor it, MAP sensor doesn't change), or if the TPS is bad (you're driving along, the TPS spikes without you actually moving the throttle, MAP sensor doesn't change because you haven't actually moved the throttle)

FrankT
03-13-06, 05:31 PM
My STS keeps blowing MAP sensors, and I can't figure out why! I know it has blown when I floor it and it bogs. It will set a code for high MAP voltage, but doesn't light the SES light. It has blown 3 times in the 3 years I have owned the car. Any ideas as to what is causing this? MAP sensors aren't cheap to replace! :eek:

CaddyDaddy,

You have an interesting case here. Here is some good news. The MAP Sensor high DTC is P0108 voltage on the signal circuit has to get over 4.9 volts for less than 1 second for this dtc to set. If the signal circuit were shorted to 12 volts it would pop the sensor. My best guess is you have an intermittent short to voltage on the signal circuit of the MAP sensor this would give you your high voltage dtc and blow your map sensor. Now the Bad news, the problem in your case is that it only happens once a year its going to be tough to duplicate it, you can try this, monitor the voltage on the MAP Sensor signal circuit while manipulating the wiring harness to see if you get a voltage spike. The green wire is the signal circuit. The Gray wire is the 5-volt reference circuit; voltage should be between 4.8 and 5.2 volts on this circuit. The orange wire is low reference basically a ground circuit through the pcm, with the ignition off and pcm powered down the resistance from the orange wire to a good ground should be less than 5 ohms.

Have fun, post your results.

Frank

Ranger
03-13-06, 09:50 PM
Now I'm confused. I thought they went from a MAP sensor on the early Northstars to a MAF sensor somewhere around '95.

eldorado1
03-13-06, 10:14 PM
96+ used MAF. Like a lot of GM engines, they used both MAF and MAP sensors. A kind of redundency I guess... MAF sensors do work well to incorporate individual differences in engines, but they are spendy. Not sure about 2000's

caddydaddy
03-14-06, 08:20 AM
My STS has a MAF and MAP sensor.