5 Volt Supply to MAP Sensor Help

GN Mistress · 05-30-2005, 04:37 PM

Does anyone know what regulates the 5 volt supply to the MAP sensor? The GM wiring diagram shows it originating at the instrument cluster, but how does it regulate the 5 volt supply? I have a 3 bar MAP that is reading high(2.10 volts) at atmosphere due to the supply voltage at 5.60 volts. It should be reading 1.66 volts at atmosphere with a supply voltage of just over 5 volts. Tested on two other cars and reads exact, so I know this one car is out of whack. This Map sensor is used to adjust tables in the F.A.S.T. therefore needs to be accurate. Thanks in advance for any help.

Steve Wood · 05-30-2005, 05:52 PM

Unlike other sensors, it does not appear to get its 5 volt supply from the ecm. Rather, it seems to take 12 volts in from the battery to the tach/boost module and outputs 5 volts to the map sensor for reference.

Therefore, I would guess it has a voltage regulator transistor that is supposed to maintain some semblance of consistency on the output. I would guess it is fading.

As John Spina repairs these units, you might give him a call tomorrow and ask him if that is the way it works. Not sure you can use the tps reference voltage supply or not as that might overload the ecm??

Kendall Frederick · 05-30-2005, 07:52 PM

Dave,

I can wire you a nice little 5v regulator from Radio Shack parts if you want..I'll be down in Orlando tomorrow.

Give me a call!

05-30-2005, 04:37 PM	#1 (permalink)
GN Mistress Registered User Join Date: Feb 2002 Location: Armadilla, FL Posts: 140	5 Volt Supply to MAP Sensor Help Does anyone know what regulates the 5 volt supply to the MAP sensor? The GM wiring diagram shows it originating at the instrument cluster, but how does it regulate the 5 volt supply? I have a 3 bar MAP that is reading high(2.10 volts) at atmosphere due to the supply voltage at 5.60 volts. It should be reading 1.66 volts at atmosphere with a supply voltage of just over 5 volts. Tested on two other cars and reads exact, so I know this one car is out of whack. This Map sensor is used to adjust tables in the F.A.S.T. therefore needs to be accurate. Thanks in advance for any help. __________________ Corvettes for lunch, Imports for dinner, looking for a midnight snack.

05-30-2005, 05:52 PM	#2 (permalink)
Steve Wood Scam Detector Enabled Join Date: Sep 2000 Location: East of Eden, Texas Posts: 41,350	Unlike other sensors, it does not appear to get its 5 volt supply from the ecm. Rather, it seems to take 12 volts in from the battery to the tach/boost module and outputs 5 volts to the map sensor for reference. Therefore, I would guess it has a voltage regulator transistor that is supposed to maintain some semblance of consistency on the output. I would guess it is fading. As John Spina repairs these units, you might give him a call tomorrow and ask him if that is the way it works. Not sure you can use the tps reference voltage supply or not as that might overload the ecm?? __________________ ------------------ A proud member of Stonewallers Against Bogus Technology Fix reason firmly in her seat, and call to her tribunal every fact, every opinion. Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blindfolded fear. Thomas Jefferson . www.vortexbuicks-etc.com

05-30-2005, 07:52 PM	#3 (permalink)
Kendall Frederick Registered User Join Date: Sep 2000 Location: Orange Park, FL Posts: 1,110	Dave, I can wire you a nice little 5v regulator from Radio Shack parts if you want..I'll be down in Orlando tomorrow. Give me a call! __________________ Kendall Frederick Orange Park, FL "More miles on the bike than in a Buick in 2005-6" SecondHand Six Racing

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