Fuel level sensor output...only to gauge or to gauge and PCM?? DTC CODE
10-16-2006, 12:22 PM
#1
Fuel level sensor output...only to gauge or to gauge and PCM?? DTC CODE Hey all. Most of you know Ive been driving my LS1 swap around for a couple weeks now. Ive been getting some small codes in the PCM...most of which I tracked down and fixed.
There are two codes that continually show up. They do not throw a check engine light...but when I scan for codes they are there. The codes are P0461 and P0463. Both have to do with the PCM looking for a signal from the fuel level sensor. They basically are telling me that I dont have the fuel level sending unit hooked to the PCM. And its correct. The fuel level wire is running right to my gauge.
Does anyone else have the fuel level wire going into the PCM??? Im thinking about splicing off the wire going to the gauge and running it over to the PCM to make it happy. I think that wire goes into one of the smaller "inside" plugs (220 and 230). So it wouldnt be too much trouble.
Just curious what everyone else did with this situation. I realize it probably wont effect much...but if hooking one wire up makes it that much closer to being "right"...then Ill do it.
Justin
P.S. Also I might add that the autometer fuel gauge isnt working for crap. I sent it back to get "reversed". But if I fill up the car when the needle isnt even at 3/4 yet...it will take almost 9 gallons. So roughly a half a tank. And it goes down really really fast when it gets close to 1/4 (actual tank level)...
Im going to call autometer on this... Another guy talked to me about it and it seemed like he was able to make something work with resistors somehow... with as popular as these cars are, youd think autometer could have reversed it and made the range right for me.
There are two codes that continually show up. They do not throw a check engine light...but when I scan for codes they are there. The codes are P0461 and P0463. Both have to do with the PCM looking for a signal from the fuel level sensor. They basically are telling me that I dont have the fuel level sending unit hooked to the PCM. And its correct. The fuel level wire is running right to my gauge.
Does anyone else have the fuel level wire going into the PCM??? Im thinking about splicing off the wire going to the gauge and running it over to the PCM to make it happy. I think that wire goes into one of the smaller "inside" plugs (220 and 230). So it wouldnt be too much trouble.
Just curious what everyone else did with this situation. I realize it probably wont effect much...but if hooking one wire up makes it that much closer to being "right"...then Ill do it.
Justin
P.S. Also I might add that the autometer fuel gauge isnt working for crap. I sent it back to get "reversed". But if I fill up the car when the needle isnt even at 3/4 yet...it will take almost 9 gallons. So roughly a half a tank. And it goes down really really fast when it gets close to 1/4 (actual tank level)...
Im going to call autometer on this... Another guy talked to me about it and it seemed like he was able to make something work with resistors somehow... with as popular as these cars are, youd think autometer could have reversed it and made the range right for me.
10-16-2006, 12:39 PM
#2
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can't help with your particular problem, but I have the gauge hooked up to my PCM with no problem (other than I wish it had some anti-slush averaging scheme). I use HPTuners on a touchscreen as my gauges interface.
10-17-2006, 09:35 AM
#3
Thanks for the input!! My gauge works ok....past full when the tank is full. At E when the tank is empty. But when the gauge says 3/4 its more like a half a tank... so the midrange is way off.
Anyway does anyone have any other info on the PCM wiring??? Did everyone just take the fuel level wire right to the guage and not hook it to the PCM??? Im going to be using a heated garage tomorrow to try to finish all the little odds and ends. It gets dark to damn fast and its been getting colder (frost) at night.
Thanks!
Justin
Anyway does anyone have any other info on the PCM wiring??? Did everyone just take the fuel level wire right to the guage and not hook it to the PCM??? Im going to be using a heated garage tomorrow to try to finish all the little odds and ends. It gets dark to damn fast and its been getting colder (frost) at night.
Thanks!
Justin
10-17-2006, 12:37 PM
#5
Hey Jeff,
Nope...using a 99 F-body PCM. I think the code mentioned something about the PCM using the fuel level to determine problems with the EVAP system or something... Since I retained the 99 EVAP system to a "T"....I want to make sure that all works the way its supposed to.
CODE P0461 = Fuel level sensor performance... And here is the part that gets me thinking...
"The PCM uses inputs from the Fuel Level Sensor in order to calculate the total fuel remaining in the fuel tank. This information is then sent to the fuel gauge. The fuel level information is also used for misfire and EVAP diagnostics"
CODE P0463 = Fuel level sensor circuit high voltage
It carries with it the same info as the code above really...
The thing is...Im not sure that the autometer gauge can work off of the PCM output for the stock 99 cluster. Probably because it is in serial data. But if the PCM wants to see the fuel level..Im inclined to show it the fuel level.
Justin
Nope...using a 99 F-body PCM. I think the code mentioned something about the PCM using the fuel level to determine problems with the EVAP system or something... Since I retained the 99 EVAP system to a "T"....I want to make sure that all works the way its supposed to.
CODE P0461 = Fuel level sensor performance... And here is the part that gets me thinking...
"The PCM uses inputs from the Fuel Level Sensor in order to calculate the total fuel remaining in the fuel tank. This information is then sent to the fuel gauge. The fuel level information is also used for misfire and EVAP diagnostics"
CODE P0463 = Fuel level sensor circuit high voltage
It carries with it the same info as the code above really...
The thing is...Im not sure that the autometer gauge can work off of the PCM output for the stock 99 cluster. Probably because it is in serial data. But if the PCM wants to see the fuel level..Im inclined to show it the fuel level.
Justin
10-17-2006, 02:35 PM
#7
Originally Posted by 70 LS1
Make sure you copy the Ohm range of the donor car and everything will work great.
Do you mean for the gauge??/ If so...I already have the autometer set up for the tank level. However it sucks. So Im thinking about getting the programmable one.
Ill have to hook the fuel level up to the PCM then...hopefully thats not causing any problems as of now... Guess we'll find out.
Justin
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10-17-2006, 08:31 PM
#8
What I meant is the PCM is looking for a certain ohm range from the stock tank level sensor. If you go out of range, they you would be right back to throwing codes. Take a look at the service manual for the donor car. You should be able to pick a resistor that is in the middle of the range and wire it up to the PCM. That would fool the PCM and you wouldn't have to mess with sending the fuel level signal to both your gauge and the PCM.
10-18-2006, 06:59 AM
#9
Hmm....good idea. Ill have to look into that. Im thinking that the PCM and EVAP system knows what kind of tank pressures occur during 1/4, 1/2, 3/4, etc. The wire for the gauge is right in my drivers side kick panel...and the blue plug that it goes to is only about 3 feet away. I might just run a wire across to it. I already have a couple single wires running to that plug...or maybe just one. I think thats the one that the speedo connects to also.
Either way...its either the white plug or the blue plug. Ill have to look into it. I dont think its hurting anything....like putting the car in LIMP mode or anything like that. haha. And Im not throwing any codes for the EVAP system. So its something Ill do when I get time. Probably when the new shifter goes in since Ill be pulling a seat and the console to do that.
Justin
Either way...its either the white plug or the blue plug. Ill have to look into it. I dont think its hurting anything....like putting the car in LIMP mode or anything like that. haha. And Im not throwing any codes for the EVAP system. So its something Ill do when I get time. Probably when the new shifter goes in since Ill be pulling a seat and the console to do that.
Justin
10-28-2006, 05:57 PM
#11
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Can't you just delete the code with HPTuners or some other software? Do you have the fuel tank pressure switch hooked up? I thought that had something to do with the EVAP and fuel level when the computer runs a diagnostic check.
10-30-2006, 07:56 AM
#12
Yeah I guess I could have the code deleted... However I retained the 99 EVAP system. Hooked it all up just like factory. So if I can make it fully operational by hooking up another wire, then no big deal. My issue is...Im hoping that the PCM isnt shutting the EVAP down because of not seeing the fuel level. I mean it threw a code so it must want it for something. But we'll see...I might just hook it up and see if the code goes away.
J.
J.
11-02-2006, 02:32 PM
#13
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Well, I read somewhere that the EVAP will be non-operational if, during the diagnostic check of the fuel system, the computer sees that the fuel tank pressure switch is non-operational or not there. I also read you can delete this code (which is what I'll be doing on my conversion) so that the computer doesn't run the diagnostic check to look for the fuel tank pressure sensor and the EVAP system will still be operational. Just a thought . . .
11-02-2006, 04:58 PM
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I would have thought that the PCM needed the signal from the pressure sensor in order to trigger the opening of the purge valve when the pressure is too high... or are you saying that it if the pressure sensor is not there it automatically opens the purge valve @ startup?
11-02-2006, 05:16 PM
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Yeah, your right the PCM needs the signal to know when to purge the system, but from what I've read it also runs a diagnostic check through the system on occasion and the switch not being there would throw a code. That's why I'm going to have the code for the pressure sensor diagnostic check removed (I don't know if that's the actual name) for my conversion so that I can continue to run the EVAP without the in-tank pressure switch. The purge will just happen at the EVAP purge solenoid according to how the PCM is programmed to do so.
11-02-2006, 05:38 PM
#16
Hold up guys...
Sounds like you all sort of veered this into a talk about the pressure sensor of the tank. Thats not the issue. The pressure sensor circuit is hooked up like its supposed to be.
My concern/issue is about the fuel LEVEL input. The PCM is asking for the input from the level sender. But Im not sure if the EVAP system is actually operating right now without the fuel level input. Right now i have the purple wire from the fuel tank, which is the sender wire, going right to my gauge. Im thinking about just running the purple wire right to the PCM..and branching off somewhere for the gauge.
The gauge works for crap anyway. haha. I might as well just use my odometer to read fuel level.
On a side note...if the EVAP system is non-operational, what are the side effects? Just emissions stuff? Would it hurt performance or fuel economy??
Justin
Sounds like you all sort of veered this into a talk about the pressure sensor of the tank. Thats not the issue. The pressure sensor circuit is hooked up like its supposed to be.
My concern/issue is about the fuel LEVEL input. The PCM is asking for the input from the level sender. But Im not sure if the EVAP system is actually operating right now without the fuel level input. Right now i have the purple wire from the fuel tank, which is the sender wire, going right to my gauge. Im thinking about just running the purple wire right to the PCM..and branching off somewhere for the gauge.
The gauge works for crap anyway. haha. I might as well just use my odometer to read fuel level.
On a side note...if the EVAP system is non-operational, what are the side effects? Just emissions stuff? Would it hurt performance or fuel economy??
Justin
