code 24 :(

[krazy2o9]

hi. i get code 24 on both my lex and stock afm. i checked the connection from the ecu plug to the harness afm plug and ther fine. the air temp senser looks like its something seperate in the afm just hanging out with afm but when i test its ports on the afm it self, the air temp part works find even when i put a little heat on it, its still in spec, but not ther other pins on the afm both lex and stock both have way to high ohms, way out of spec. so my question is would the pins 3,4,5 have any effecs in code 24 poping up, and thats the only code i have. even water temp senser to pin 1 in the afm is working.

could it just be the ecu?

 

[hvyman]

Doubt its the ecu(though it is possible but highly unlikely). If the afm is out of spec at all it needs to be replaced.

 

[krazy2o9]

ok, for sure.

 

[krazy2o9]

just another question, about the afm, was looking at my repair manual and for 89 and up turbo modles to check only the tha-e2 the temp senser, and my supra is a 90 so was wondering if the rest of the afm even needs to be check such as (ks to e1) (e1 to ks) (vc to e1) (e1 to vc) the way 87 to 88 are checked. and what p/n should i get for the 1990 modle 42010 or 42011. i belive its the 10 and not the 11 one.

 

[hvyman]

42011. Fyi there about 4-600 new.

Tha-e2 is for the air temp sensor. Everything else is for the afm.

 

[Flipkronikz]

Had the same code. Replaced and now runs like a champ

 

[CyFi6]

For code 24 the only part of the AFM you need to check is the temperature sensor.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96

Sounds like you already did, but I'm not certain. Once you know the sensor is good you need to make sure your wiring is good. E2 wire should have voltage reference to it with the key on and THA should have continuity to the ECU connector without any shorts to ground or power.

 

[krazy2o9]

with the key on (tha) on the harness has 4.99v and e2 shows .02v.

 

[CyFi6]

My mistake, 5V is normal on THA (EDIT: With the AFM unplugged). Check continuity between E2 pin of the AFM connector and E2 at the ECU connector under the dash. (This is assuming you already checked the actual temp sensor in the AFM)

Heres a little visual of the circuit.

If the ECU sees either 5V or 0V (at the "Voltage Temp. Signal" it will set that code. Any short to ground on THW or open in the circuit can cause that. You already verified that THA (THW in the pic) has no short or open so you need to check the sensor and E2 for opens.

 

[jetjock]

with the key on (tha) on the harness has 4.99v and e2 shows .02v.

That's why you're getting the code. The circuit is open.

 

[3p141592654]

THA is pulled up internal to the ECU to 5V (as the little cartoon shows). Working correctly, THA will be always be lower than 5V. However, when THA is open circuit, you will see 5V on it at the ECU.

 

[CyFi6]

Assuming he checked THA at the AFM connector with it unplugged rather than backprobed, 5v would be expected and would indicate there is no open (could still be high resistance I suppose) or short on THA between the ECU and the AFM connector.

 

[3p141592654]

That is correct. I assumed he measured it with the AFM attached, but re-reading his post it is unclear.

 

[jetjock]

I assumed the same since it would be the logical first step and there isn't much diagnostic value to doing it otherwise.

 

[krazy2o9]

ill test it with it pluged in when i get back home. will be home in about 3 days

ill be replacing thows 2 wires maybe if can figer nothing else out and see whats up with the ground