Fuel level wiring for Flex engine
Fuel level wiring for Flex engine I have a 2006 L59 flex engine that I plan on keeping ethanol capable. To stay flex capable my understanding is that the PCM needs fuel level. My sender is GM (correct ohm rating). If I run two wires from the sender, one to the PCM and one to the fuel gauge, will it work, or will they interfere with each other?
In the past the only thing the fuel level is used for is two fold. One with the newer pcms the fuel gauge is serial data from the pcm to the instrument cluster. It is used to determine at what point the pcm needs to run the evap diagnostic tests. What type of vehicle is it going into. You may be able to adapt the sender in order to get it to work correctly. I need to do some reading on the flex stuff but I think it should function fine with or without the sending unit input to the pcm.
It needs the fuel level because it doesn't have a flex fuel sensor as the older (prior 2006) L59's had. Say you have a half of tank of gas and go fill up the rest with ethanol. The pcm then calculates based on o2 reading and fuel level. I just don't know if hooking a gauge and the pcm and to the sender will render one of them inop.
Teching In
Joined: Sep 2005
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You say your engine is 2006 but are you sure? 2006 is the last year GM used fuel composition sensors on their flex fuel vehicles. This is also the last year for the 24X crank reluctor and matching 160 pin Gen 3 PCM in the trucks. If you have this set up then the PCM needs to see a 5 volt square wave signal from the fuel composition sensor in order to command the correct air/fuel ratio for the fuel being burnt. With out the signal the PCM will revert to an air/fuel that is known the engine will survive if running ethanol or gasoline; very rich.
2007 vehicles use fuel level and fuel tank pressure to calculate ethanol percentage of the fuel. The engines are also 58X crank reluctor and use the E38 PCM with an external trans controller.
So, which do you have?
2007 vehicles use fuel level and fuel tank pressure to calculate ethanol percentage of the fuel. The engines are also 58X crank reluctor and use the E38 PCM with an external trans controller.
So, which do you have?
They started using the virtual sensor (PCM control) in 2006. I'm not sure if some 2006 models still had the actual composition sensor, but from what I've seen and read 2006's are virtual.
My PCM is the type with two long plugs (green, blue). Not sure if its a E40?
My PCM is the type with two long plugs (green, blue). Not sure if its a E40?
Here's a breakdown of who had which. Pulled this from GM's TSB's for an update to pcm.Campaign - ECM Updates for Virtual Flex Fuel Sensor
Subject:
Service Update for Inventory and Customer Vehicles-E85 Virtual flex fuel Sensor (VFFS) Update-Reprogram ECM
# 06162C - (09/12/2007)
Models:
2006 Chevrolet Impala, Monte Carlo, Silverado, Avalanche, Tahoe, Suburban
2006 GMC Sierra, Yukon, Yukon XL
2007 Buick Terraza
2007 Chevrolet Impala, Monte Carlo, Uplander, Silverado Classic, Tahoe, Suburban, Avalanche, Silverado, Express
2007 GMC Sierra Classic, Yukon, Yukon XL, Sierra, Savana
2007 Pontiac Montana SV6
Subject:
Service Update for Inventory and Customer Vehicles-E85 Virtual flex fuel Sensor (VFFS) Update-Reprogram ECM
# 06162C - (09/12/2007)
Models:
2006 Chevrolet Impala, Monte Carlo, Silverado, Avalanche, Tahoe, Suburban
2006 GMC Sierra, Yukon, Yukon XL
2007 Buick Terraza
2007 Chevrolet Impala, Monte Carlo, Uplander, Silverado Classic, Tahoe, Suburban, Avalanche, Silverado, Express
2007 GMC Sierra Classic, Yukon, Yukon XL, Sierra, Savana
2007 Pontiac Montana SV6
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Teching In
Joined: Sep 2005
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The PCM you have is for 24X engines. It is not an E40 as they have three connectors on the top (grey/black/blue) and look just like the 58X E38 that most new GM vehicles currently use except the connectors are different.
I have a friend at GM checking to see if there is paperwork with a year break for when the inline FCS was replaced by the fuel tank level/pressure algorithm. Factory service manuals have this year break at 2006/2007. Hopefully he will come back with a definite year/month.
Two viable options you should look at:
1. If your PCM does have the VFFS program and you want to keep E85 capabilities then plan on installing the fuel level sender and fuel tank pressure sensor in addition to what ever level sender your dash needs. This still might not work because of different tank volume and physical aspects which could throw the VFFS algorithm off. You might find someone with HPTuners to see if the VFFS has a table that can be modified to counter the differences between your tank and the factory L59 tank.
Option 2. Change out your PCM to one that uses the square wave signal from a FCS. Install an FCS to your vehicle. Walk in dealer price for an FCS is around $750 so prepare your wallet ahead of time or try the salvage yards.
I have a friend at GM checking to see if there is paperwork with a year break for when the inline FCS was replaced by the fuel tank level/pressure algorithm. Factory service manuals have this year break at 2006/2007. Hopefully he will come back with a definite year/month.
Two viable options you should look at:
1. If your PCM does have the VFFS program and you want to keep E85 capabilities then plan on installing the fuel level sender and fuel tank pressure sensor in addition to what ever level sender your dash needs. This still might not work because of different tank volume and physical aspects which could throw the VFFS algorithm off. You might find someone with HPTuners to see if the VFFS has a table that can be modified to counter the differences between your tank and the factory L59 tank.
Option 2. Change out your PCM to one that uses the square wave signal from a FCS. Install an FCS to your vehicle. Walk in dealer price for an FCS is around $750 so prepare your wallet ahead of time or try the salvage yards.
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Verdad Gallardo Thanks. I plan on adding the pressure sensor anyway. I guess I will hook up my gauges first, then attempt to hook up the pcm fuel level wire....see what happens.
I definately won't go the FCS route...even though I've seen them on Ebay for $200.
I definately won't go the FCS route...even though I've seen them on Ebay for $200.
Teching In
Joined: Sep 2005
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The year break is definitely at 2005/2006 for the FCS to VFFS change over. If you cannot get the fuel pressure/level sensors to work correctly with your setup you can always get a 2005 PCM and install the FCS. You will just need to add the signal wire between the two, and power and ground. PM me your email and I will send you the Ohm specifications of a 2006 pickup fuel sender.
Teching In
Joined: Mar 2009
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I am doing similar conversion, using 2006 5.3L L59 Vortec out of a Silverado. Engine has the virtual flex fuel setup. I'm not sure what the resistance of the fuel level sensor was, or if the sensor output a voltage instead of resistance change. Do you have that info?
Thanks
Thanks
