Code 24 w/maft pro
- Thread starter spooln30
- Start date
code 24 has to do w/the ECU booting up and checking for the intake air temp sensor before the MAFT pro has booted up and output the signal to the ECU (unless of course you have the MAFT pro hooked up incorrectly...). the code is really meaningless since the signal is supplied to the ECU. if you're really annoyed you can simply put a resistor across THA and E1 or you can wire the MAFT pro to be powered in the ACC position....
All is hooked up to correct locations and soldered. Does eveyone get that code(24) with a Maft Pro?
And thanks for the info.
Later Keith
And thanks for the info.
Later Keith
JimR;1031051 said:
Adam correct me if I am regurgitating this wrong buttt......
You cannot have the Maft pro THA output hooked up as well as having the resistor hooked up. That still throws the code.
Its one or the other.
If you would like to use the output of the Maft pro then you need to connect the power lead of the Maft pro to be on in the accessory, ignition, and start positions which can be done with an accessory source, an ignition source, and a diode.
If you would like to use the resistor method, simply disconnect the THA output of the Maft pro and be done
Just a note for any N/A guys who read this. A single resistor across E1 and THA will NOT resolve the code for the GE ECU. If you wish to use a resistor you'll need to use two of the same value. One goes across E1 and THA and the other across VC and THA. If you run it this way you do NOT connect the MAFT Pro's output to the THA input on the TCCS.
Also, wiring for power from ACC never worked on any of the installs I've done. ACC loses power when cranking. I'm working on a small circuit to boot the pro and hold it high using an initial trigger from the ACC switch, but it's not powered from there.
Also, wiring for power from ACC never worked on any of the installs I've done. ACC loses power when cranking. I'm working on a small circuit to boot the pro and hold it high using an initial trigger from the ACC switch, but it's not powered from there.
I understand... it could've been voltage drop, the diodes I was trying to use (1N4002, IIRC), or the relays I was using but the relays would continuously stumble while cranking. This was on two different cars (one GE and one GTE), on the third (GTE) we just used two resistors on the THA line to supply ~2.4v and all was well... the N/A is MUCH more picky than the GTE as well.
IIRC, with the GTE you just need to supply the ECU with a THA signal right away and you're good... with the GE it requires THA AND VS right away, so you need to power the Pro first and the signal can't stumble enough to cause a code.
Sorry if I'm adding any confusion for the GTE guys, but I've dealt with both platforms. Regardless, the two resistors is by far the simplest fix for the THA signal, you can put them in at the AFM's harness connector.
IIRC, with the GTE you just need to supply the ECU with a THA signal right away and you're good... with the GE it requires THA AND VS right away, so you need to power the Pro first and the signal can't stumble enough to cause a code.
Sorry if I'm adding any confusion for the GTE guys, but I've dealt with both platforms. Regardless, the two resistors is by far the simplest fix for the THA signal, you can put them in at the AFM's harness connector.
I'm going to digress a little here.... I am definately running with the maftpro hooked up to THA, and that won't change soon, so a resistor is out of the question.
However, that code 24 (and the related code 35) are really not much of a nuisance. It's the code 21 caused by having no stock 02 sensor that is definately a pain, because that causes the CEL to illuminate and stay that way. I would love to solve this one in a safe manner (electrically speaking).
However, that code 24 (and the related code 35) are really not much of a nuisance. It's the code 21 caused by having no stock 02 sensor that is definately a pain, because that causes the CEL to illuminate and stay that way. I would love to solve this one in a safe manner (electrically speaking).
JimR;1033116 said:
Excellent! It is good to have convictions and better yet to actually stand by them.... :nuts:
JimR;1033116 said:
Well, since you've obviously got a problem with resistors (don't blame ya... little monsters if you ask me... always standing in the way of progress) I won't point out that BigAaron does mention a fix in this thread: http://www.supramania.com/forums/showthread.php?t=6950&highlight=code+21
I'll instead recommend that you go buy an O2 sensor emulator.... if you can find one: http://www.usdoj.gov/opa/pr/2007/July/07_enrd_490.html
Otherwise you'll need to build a small circuit to supply a signal of about .5v to the ECU so it thinks it's running stoichiometric.
DocJ or JJ - I've read that the 89+ are the ones with the issue concerning this code when the sensor is disconnected... why won't just grounding that line work?
Hold up a second.... I'm not leaving the maftpro hooked up to THA "just because", or for some strange conviction
I just hadn't realized yet that the resistor will actually replace what the maftpro is doing for the air temp signal.
Is this the resistor you're talking about for dealing with the 02 heater circuit?
I just hadn't realized yet that the resistor will actually replace what the maftpro is doing for the air temp signal.
Is this the resistor you're talking about for dealing with the 02 heater circuit?
bigaaron said:
I was just joking about the whole reluctance thing. The solution using two resistors in a network replaces the MAFT Pro's feed to THA. One less wire to run and it supplies 2.5v as soon as the ECU boots so no issues with the MAFT Pro not providing that signal soon enough.
I haven't had to deal with a 89+ GTE so I don't know the specifics... just recall that the issue with the O2 sensor did have a solution which has been discussed. I could be wrong about there being a final solution it's been a while since I've looked at all my notes.... particularly those pertaining to the GTE.
I haven't had to deal with a 89+ GTE so I don't know the specifics... just recall that the issue with the O2 sensor did have a solution which has been discussed. I could be wrong about there being a final solution it's been a while since I've looked at all my notes.... particularly those pertaining to the GTE.
Heheh, I had a good laugh at your sense of humour, after feeling misunderstood and frustrated first. lol.
My mind was going in the track that the Maftpro supplies a voltage, which a resistor couldn't possibly replace. But I forgot that the ECU is actually supplying the voltage normally, and that the air temp sensor is a temperature sensitive resistor anyway.
Warning... the following could be ass-backwards! I'm still a little fuzzy on how the electricity is flowing in this circuit. If someone could clear up these questions that would be great! Here they are: Is the ECU normally supplying 5volts on THA to the air temp resistor? When that current (I'm talking conventional current, not electron flow) flows through the brown wire to the maftpro, is the maftpro actually reading that voltage and stepping it down with some sort of variable resistor to the 2.51v set in its configuration?
Right, back on track. Referring to FI-96 in the 1990 TSRM, I'd like to point out that the connection is between THA and E2, not E1 as previously posted. Since they are both ground points, it is probably irrelevant, but we may as well get on the same page when referencing connections to the ECU. I guess the other possibility is that it's E1 on a GE or pre-89 system?
Secondly, referring to that same page, I reckon we want a resistor (or equivalent with 2 or more) to hit the 2500ohm/20c air temperature listed. Since the Maftpro documentation gives a recommended value of 2.51v for Vout1, that should do the trick nicely. If memory serves, was a 2200ohm resistor recommended earlier? How much extra resistance would normally occur from the wires themselves?
P.S. I love my car-sound 3" catalytic converter, and that's something I will take a stand on!
Cheers,
Jim
My mind was going in the track that the Maftpro supplies a voltage, which a resistor couldn't possibly replace. But I forgot that the ECU is actually supplying the voltage normally, and that the air temp sensor is a temperature sensitive resistor anyway.
Warning... the following could be ass-backwards! I'm still a little fuzzy on how the electricity is flowing in this circuit. If someone could clear up these questions that would be great! Here they are: Is the ECU normally supplying 5volts on THA to the air temp resistor? When that current (I'm talking conventional current, not electron flow) flows through the brown wire to the maftpro, is the maftpro actually reading that voltage and stepping it down with some sort of variable resistor to the 2.51v set in its configuration?
Right, back on track. Referring to FI-96 in the 1990 TSRM, I'd like to point out that the connection is between THA and E2, not E1 as previously posted. Since they are both ground points, it is probably irrelevant, but we may as well get on the same page when referencing connections to the ECU. I guess the other possibility is that it's E1 on a GE or pre-89 system?
Secondly, referring to that same page, I reckon we want a resistor (or equivalent with 2 or more) to hit the 2500ohm/20c air temperature listed. Since the Maftpro documentation gives a recommended value of 2.51v for Vout1, that should do the trick nicely. If memory serves, was a 2200ohm resistor recommended earlier? How much extra resistance would normally occur from the wires themselves?
P.S. I love my car-sound 3" catalytic converter, and that's something I will take a stand on!
Cheers,
Jim
Last edited:
"Our JetJock, who art in (flying flying through actually) heaven, forgive me this day my dumbed down explanation of the following as i forgive the ignorance and foolishness that abounds in those before me..."
Right, E2 is the sensor ground and E1 is the computer ground.... in this case any ground would work fine as all that we're looking to do is provide a static signal of a given value (actually the value we're supplying isn't horribly critical, but 2.5v is about where you want it optimally). If you want to get technical I think VC is usually closer to 4.8v in which case this setup will give you a constant 2.4v.... trust me it's fine.
A resistor network (aka voltage divider, although this term is not always correct) is where you employ multiple resistors to control voltage and/or current (this is the simplified explanation by the way). When you bridge across a + voltage line and ground using two equal value resistors you get half the voltage at the point between those two resistors when you test that point against either the source + or the ground.
Basic network
This is actually how the THA signal is generated... it's also how the TPS' signal is generated except that the two resistors essentially change in size by the change in the position of the wiper (the wiper represents the center point between the two resistors in a fixed circuit).
The value of the resistors will not effect the voltage if the percentages are maintained. For example if you have a 5v supply and need 2.5v output you can use either a pair of 100 Ohm resistors, a pair of 1K Ohm resistors or even a pair of 1M Ohm resistors. What changes in this case is the amperage supplied, but the voltage in all three cases would still be 2.5v.
If you need a value to go with for this purpose use a pair of 1.2K Ohm resistors... they're common enough and you can be confident they'll work fine because I just told you they will.
Right, E2 is the sensor ground and E1 is the computer ground.... in this case any ground would work fine as all that we're looking to do is provide a static signal of a given value (actually the value we're supplying isn't horribly critical, but 2.5v is about where you want it optimally). If you want to get technical I think VC is usually closer to 4.8v in which case this setup will give you a constant 2.4v.... trust me it's fine.
A resistor network (aka voltage divider, although this term is not always correct) is where you employ multiple resistors to control voltage and/or current (this is the simplified explanation by the way). When you bridge across a + voltage line and ground using two equal value resistors you get half the voltage at the point between those two resistors when you test that point against either the source + or the ground.
Basic network
This is actually how the THA signal is generated... it's also how the TPS' signal is generated except that the two resistors essentially change in size by the change in the position of the wiper (the wiper represents the center point between the two resistors in a fixed circuit).
The value of the resistors will not effect the voltage if the percentages are maintained. For example if you have a 5v supply and need 2.5v output you can use either a pair of 100 Ohm resistors, a pair of 1K Ohm resistors or even a pair of 1M Ohm resistors. What changes in this case is the amperage supplied, but the voltage in all three cases would still be 2.5v.
If you need a value to go with for this purpose use a pair of 1.2K Ohm resistors... they're common enough and you can be confident they'll work fine because I just told you they will.
Update on my startup issue (ie. code 31: yes, 31, N/A remember).
I put together another harness with two diodes to power my MAFT Pro from Acc and IGN and it worked. I used 1N4002 diodes, which I swear I tried before, but perhaps I had a couple bad ones or they were in the wrong bin. Everything's working like a charm now.
So, two resistors and two diodes and you've got no more codes and still have one V-out left for using an additional feature like 5.x's Enhanced TPS function.
I put together another harness with two diodes to power my MAFT Pro from Acc and IGN and it worked. I used 1N4002 diodes, which I swear I tried before, but perhaps I had a couple bad ones or they were in the wrong bin. Everything's working like a charm now.
So, two resistors and two diodes and you've got no more codes and still have one V-out left for using an additional feature like 5.x's Enhanced TPS function.