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Pulled codes

  • Thread starter Thread starter greenjams
  • Start date Start date Nov 26, 2007
G

greenjams

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Jul 13, 2004
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Houston,TX
Nov 26, 2007
#1
  • Nov 26, 2007
  • #1
I pulled the codes from my 1994 mustang gt and i got.

311 ( thermactor air system inoperative ) right

314 ( thermactor air system inoperative ) left

So does anyone have any idea what that means or what i have to replace.

Thanks
 

bloopbloob

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Sep 27, 2006
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Alberta
Nov 26, 2007
#2
  • Nov 26, 2007
  • #2
thats just the proper name for the smog pump. is it still hooked up? i just saw a writeup from jrichker about the tad/tab solenoids. you might want to check those also.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
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Nov 27, 2007
#3
  • Nov 27, 2007
  • #3
And you'll find the solenoids in the passenger side fender. Remove the wheel liner to access them.

Speaking of a totally different system, while in there, inspect your charcoal cannister lines (the CC is right under the antenna). The lines (especially the purge line) rot.
 

jrichker

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#4
  • Nov 27, 2007
  • #4
The codes refer to the electrical solenoids that operate the Thermactor Air System (smog pump) control valves. Often people will remove the solenoid valves in a foolish attempt ot make the car faster. If the car has catalytic converters, this results in damaging the converters so that they fail and clog. This make the car run even slower.

The following is an explanation of how the Thermactor Air system works. The wiring color codes for the solenoid control valves may be different in a 94-95 Mustang, so don't let that throw you off course.

Some review of how it works...

The Thermactor air pump (smog pump) supplies air to the heads or catalytic converters. This air helps break down the excess HC (hydrocarbons) and CO (carbon monoxide). The air supplied to the catalytic converters helps create the catalytic reaction that changes the HC & CO into CO2 and water vapor. Catalytic converters on 5.0 Mustangs are designed to use the extra air provided by the smog pump. Without the extra air, the catalytic converters will clog and fail.

The Thermactor air pump draws air from an inlet filter in the front of the pump. The smog pump puts air into the heads when the engine is cold and then into the catalytic converters when it is warm. The Thermactor control valves serve to direct the flow. The first valve, TAB (Thermactor Air Bypass) or AM1 valve) either dumps air to the atmosphere or passes it on to the second valve. The second valve, TAD (Thermactor Air Diverter valve or AM2 valve) directs it to the heads or the catalytic converters. Check valves located after the TAB & TAD solenoids prevent hot exhaust gases from damaging the control valves or pump in case of a backfire. The air serves to help consume any unburned hydrocarbons by supplying extra oxygen to the catalytic process. The computer tells the Thermactor Air System to open the dump valve at WOT (wide open throttle) minimizing engine drag. The dump valve reduces the parasitic drag caused by the smog pump to about 2-4 HP at WOT.






Computer operation & control for the Thermactor Air System
Automobile computers use current sink technology. They do not source power to any relay, solenoid or actuator like the IAC, fuel pump relay, or fuel injectors. Instead the computer provides a ground path for the positive battery voltage to get back to the battery negative terminal. That flow of power from positive to negative is what provides the energy to make the IAC, fuel pump relay, or fuel injectors work. No ground provided by the computer, then the actuators and relays don't operate.

One side of the any relay/actuator/solenoid in the engine compartment will be connected to a red wire that has 12-14 volts anytime the ignition switch is in the run position. The other side will have 12-14 volts when the relay/actuator/solenoid isn't turned on. Once the computer turns on the clamp side, the voltage on the computer side of the wire will drop down to 1 volt or less.

In order to test the TAD/TAB solenoids, you need to ground the white/red wire on the TAB solenoid or the light green/black wire on the TAD solenoid.

To test the computer, you can use a test light across the TAB or TAD wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
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Nov 27, 2007
#5
  • Nov 27, 2007
  • #5
To help a little with the colors (since they can be different, as Jrichker noted)...........

On a '94, the the wire in Jrichker's diagram that's W/R (TAB control) is W/O (Pin 31 on the PCM).

The Grn/Blk wire on Jrichker's diagram (TAD control) should be brown (pin 34 at the PCM).
 
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