check engine light flashes on and off randomly
11-18-2006, 09:57 PM
#11
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Join Date: Oct 2006
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Posts: 510
RE: check engine light flashes on and off randomly
ORIGINAL: PJB
Due to the location of the plugs its hard to drive with a scanner connected.
Due to the location of the plugs its hard to drive with a scanner connected.
Just run the wire out the corner of the hood and into the window.
11-18-2006, 10:07 PM
#12
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Join Date: Aug 2006
Location: Rotterdam, NY
Posts: 3,333
RE: check engine light flashes on and off randomly
ORIGINAL: mattdel
there are 4 sensors, the front 2 are for air/fuel ratio, and the rear 2 monitor catalyst efficiency. thats why o/r h-pipes cause check engine lights. no cats = 0% efficiency.
there are 4 sensors, the front 2 are for air/fuel ratio, and the rear 2 monitor catalyst efficiency. thats why o/r h-pipes cause check engine lights. no cats = 0% efficiency.
11-18-2006, 10:45 PM
#16
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Location: Rotterdam, NY
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RE: check engine light flashes on and off randomly
I just pulled codes and got the following:
31- EVP - EVP signal is/was out of range - EVP
63- Throttle Position Sensor (TPS) signal too low TPS
79-A/C is on or pin 10 is shorted to power
I replaced the TPS and set it to the correct voltage a few days ago so that should be an old stored code. I just double checked the voltage and its right at .9 KOEO.
The defroster was on so that explains code 79.
That leaves code 31. Im not sure what that one is all about.
31- EVP - EVP signal is/was out of range - EVP
63- Throttle Position Sensor (TPS) signal too low TPS
79-A/C is on or pin 10 is shorted to power
I replaced the TPS and set it to the correct voltage a few days ago so that should be an old stored code. I just double checked the voltage and its right at .9 KOEO.
The defroster was on so that explains code 79.
That leaves code 31. Im not sure what that one is all about.
11-18-2006, 11:41 PM
#17
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Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
RE: check engine light flashes on and off randomly
1. The only 5.0L OBD-I Mustangs with datastream capabilities are the '94-'95's...they don't have a freeze-frame option like OBD-II's. It's not a function of the scanner in use, it's a function of the ECM.
2. OBD-I Stangs use 2-O2 sensors, no downstream O2's like in OBD-II setups.
3. Codes 31 and 63 may be related, both sensors (TPS, EVP) share VREF and SIGRTN circuits. A problem in the EVP sensor (short circuit), will affect TPS readings @part-throttle....something like......
4. Check the output voltage of the EVP sensor (just like you did for the TPS), ign on engine off....if EVP signal voltage output is below .24vdc....EVP would need to be replaced. FYI Code 31 = EGR Valve Position/Pressure Feedback EGR Circuit Below Minimum Voltage. 0.24 volts (O,CM,R)
Hope this helps....
2. OBD-I Stangs use 2-O2 sensors, no downstream O2's like in OBD-II setups.
3. Codes 31 and 63 may be related, both sensors (TPS, EVP) share VREF and SIGRTN circuits. A problem in the EVP sensor (short circuit), will affect TPS readings @part-throttle....something like......
4. Check the output voltage of the EVP sensor (just like you did for the TPS), ign on engine off....if EVP signal voltage output is below .24vdc....EVP would need to be replaced. FYI Code 31 = EGR Valve Position/Pressure Feedback EGR Circuit Below Minimum Voltage. 0.24 volts (O,CM,R)
Hope this helps....
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