MAP sensor
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Cargo Master
Joined: Aug 2004
Posts: 3,455
Likes: 8
From: Williams Lake B.C.
MAP sensor
Is the MAP sensor in the same place on a 91 diesel as it is on a 95?
On the firewall on the passengers side?
My neighbour has a parts truck and I looked for the sensor and could find it there?
On the firewall on the passengers side?
My neighbour has a parts truck and I looked for the sensor and could find it there?
Elder User
Joined: Jan 2008
Posts: 698
Likes: 0
From: Guymon
I din't think we used a MAP sesnor in the 7.3IDI (like in the 91), just for the powerstrokes I thought.(like in the 95)
I got something that looks like a map sensor right below the right wiper arm area on the passenger side. The hose is broke off or there was never one there, just a gray clip with 3 wires. Not sure what it is though and never really though about it.
I got something that looks like a map sensor right below the right wiper arm area on the passenger side. The hose is broke off or there was never one there, just a gray clip with 3 wires. Not sure what it is though and never really though about it.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
That is a low vacuum warning switch, should turn the brake light in the dash on if you loose vacuum to power your brakes and run the heater controls.
With no throttle plate, the only vacuum an IDI diesel has is what is created by a dirty air filter.
Vacuum for the brakes is supplied by the vacuum pump, not the intake manifold.
With no throttle plate, the only vacuum an IDI diesel has is what is created by a dirty air filter.
Vacuum for the brakes is supplied by the vacuum pump, not the intake manifold.
Elder User
Joined: Jan 2008
Posts: 698
Likes: 0
From: Guymon
That particular sensor for the brakes I think is above the driver side wheel well, On mine anyway.. I almost know it its cause I broke the tit off where the vac line connects to the sensor while changing the water pump, now my brake warning light wont go out. Now I have to know exactly what that sensor is. Unless it has 2 sensors... I will do some reasearch and get a part number off it. Its got me thinking. Till then, good luck.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Three wire going to it.
92 and later F series
Black = ground
Red yellow = ignition power
Dark green light green = output to dash light
Looks like the dark green /light green goes to ground to turn the light on.
RABS, brake fluid level, parking brake and low vacuum switch all tie together to turn it on.
Also looks like fuse 17 supplies power, but don't know what else that would take out.
92 and later F series
Black = ground
Red yellow = ignition power
Dark green light green = output to dash light
Looks like the dark green /light green goes to ground to turn the light on.
RABS, brake fluid level, parking brake and low vacuum switch all tie together to turn it on.
Also looks like fuse 17 supplies power, but don't know what else that would take out.
Elder User
Joined: Jan 2008
Posts: 698
Likes: 0
From: Guymon
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Postmaster
Joined: Apr 2008
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Actually folks, we do have a MAP-type sensor, only tis actually a barometric sensor to measure the ambient air pressure, I think the PCM uses it as an input in determine the shift schedule. In my truck that sensor lives on the firewall, between the A/C box and the engine air filter housing.
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Elder User
Joined: Aug 2007
Posts: 728
Likes: 0
it is a BARO sensor and it is mounted on the a/c box below the right wiper
it is there for barometric sensor reading to aid in transmission shift scheduling
it is only on automatic E4OD vehicles
the 95 is a powerstroke and it is a manifold absolute pressure sensor for engine control fuction
it is there for barometric sensor reading to aid in transmission shift scheduling
it is only on automatic E4OD vehicles
the 95 is a powerstroke and it is a manifold absolute pressure sensor for engine control fuction
Elder User
Joined: Aug 2007
Posts: 728
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actually it is there to cause the transmission to shift a little earlier at higher altitude when looking at the throttle demand versus road speed
the engien has power loss at altitude and throttle demand is higher and can cause a scenario where the engine is at high rpm with no upshift so to speak plus it would have a harsh upshift
the engien has power loss at altitude and throttle demand is higher and can cause a scenario where the engine is at high rpm with no upshift so to speak plus it would have a harsh upshift
Logistics Pro
Joined: Jun 2009
Posts: 4,116
Likes: 6
From: metairie, LA
That is a low vacuum warning switch, should turn the brake light in the dash on if you loose vacuum to power your brakes and run the heater controls.
With no throttle plate, the only vacuum an IDI diesel has is what is created by a dirty air filter.
Vacuum for the brakes is supplied by the vacuum pump, not the intake manifold.
With no throttle plate, the only vacuum an IDI diesel has is what is created by a dirty air filter.
Vacuum for the brakes is supplied by the vacuum pump, not the intake manifold.