1997 Ford F-150 error code

Tiny
NICCID24
  • MEMBER
  • 1997 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 190,000 MILES
I got an error code tell me "idel air control underspeed" these code things are great but they don't tell you how to fix it. Is this something I can do myself? I love my truck and this is the first problem I have had with it sence I got the truck in '98. Can I fix it my self?
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Wednesday, September 3rd, 2008 AT 7:03 PM

3 Replies

Tiny
BMRFIXIT
  • EXPERT
What do u have for p code #
let me know and I will try to get you the steps
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Wednesday, September 3rd, 2008 AT 8:09 PM
Tiny
NICCID24
  • MEMBER
The code is a P1507 pending
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Thursday, September 4th, 2008 AT 12:12 AM
Tiny
BMRFIXIT
  • EXPERT
1997 Ford Pickup F150

CIRCUIT TEST KE - IDLE AIR CONTROL (IAC) VALVE

Diagnostic Aids
Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:
Throttle linkage.
Wiring harness circuits (IAC and VPWR).
Faulty Idle Air Control (IAC) valve.
Faulty throttle body.
Faulty Powertrain Control Module (PCM).

1) DTC P0505, P1504 Or P1507 Perform KOER self-test. If DTC P0505, P1504 or P1507 is present, go to next step. If DTC P0505 or P1507 is not present, IAC system is okay and testing is complete.
2) DTC P0505 & P1507 DTC P0505 indicates that IAC system malfunction has been detected. DTC P1504 indicates that IAC circuit malfunction has been detected. DTC P1507 indicates that IAC system under speed fault has been detected. Possible causes are as follows:

? IAC circuit open or shorted to PWR.
? VPWR circuit open.
? Contaminated IAC valve assembly.
? Damaged throttle body.
? Faulty PCM.

Turn ignition off. Disconnect IAC solenoid. Turn ignition on. Measure voltage between VPWR terminal of IAC solenoid wiring harness connector and battery ground terminal. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open VPWR circuit and repeat QUICK TEST.
3) Check IAC Solenoid Resistance Turn ignition off. Connect DVOM positive lead to VPWR terminal of IAC solenoid wiring harness connector. Connect DVOM negative lead to IAC terminal. If resistance is 6-13 ohms, go to next step. If resistance is not 6-13 ohms, replace IAC valve assembly and repeat QUICK TEST.
4) Check IAC Solenoid Internal Short To Case Turn ignition off. Measure resistance between each wiring harness connector terminal and IAC housing. If each resistance is 10,000 ohms or more, go to next step. If either resistance is less than 10,000 ohms, replace IAC solenoid assembly and repeat QUICK TEST.
5) Check Air Inlet System Turn ignition off. Remove air filter. Inspect air filter, MAF sensor and air inlet system for excessive dirt or contamination. Repair or replace as necessary and repeat QUICK TEST. If air filter is okay, go to next step.
6) Check For Vacuum Leaks Start engine and allow to idle. Inspect air inlet system any of the following possible faults:

? Cracked or punctured air inlet tube.
? Loose inlet air tube or air cleaner housing.
? Loose or damaged throttle body.
? Contaminated or damaged IAC valve assembly.
? Faulty EGR valve or gasket.
? Faulty PCV valve or hose.
Check entire system for vacuum leaks. Repair or replace as necessary. If no vacuum leaks are found, go to next step.
7) Check IAC Circuit Continuity Leave ignition off. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between breakout box test pin No. 83 (IAC) and IAC terminal at IAC solenoid wiring harness connector. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.
8) Check IAC Circuit For Short To Power Turn ignition on. Measure voltage between breakout box test pin No. 83 (IAC) and chassis ground. If voltage is one volt or more, repair circuit short to power and repeat QUICK TEST. If voltage is less than one volt, go to next step.
9) Check IAC Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 83 (IAC) and test pins No. 51 and 103 (PWR GND) at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair circuit short to ground and repeat QUICK TEST.
10) Check IAC Signal From PCM Leave ignition off. Connect PCM to breakout box. Connect IAC solenoid to wiring harness connector. Connect DVOM between test pin No. 83 (IAC) and test pin No. 51 (PWR GND) at breakout box. Start engine and slowly increase speed to 3000 RPM. If voltage is 3.0-11.5 volts, remove IAC solenoid and check throttle body. If throttle body is okay, replace IAC assembly and repeat QUICK TEST. If voltage is not 3.0-11.5 volts, replace PCM and repeat QUICK TEST.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 20). No test procedures have been omitted.
20) DTC P1506 This code indicates that IAC system has reached over speed malfunction. Possible causes are as follows:
? IAC circuit short to ground.
? IAC assembly stuck open.
? Air intake leaks or restrictions.
? Damaged throttle body.
? Contaminated or damaged IAC valve assembly.
? Faulty Powertrain Control Module (PCM).
Check entire system for vacuum leaks. Repair or replace as necessary. If no vacuum leaks are found, go to next step.

Solenoid. Attach vacuum pump with gauge to carbon canister hose port. See Fig. 82. Using vacuum pump, apply 16 in. Hg to port. If vacuum bleeds off within 20 seconds, replace EVAP canister purge valve or solenoid and repeat QUICK TEST. If vacuum is not bled off immediately, go to next step.
Fig. 82: EVAP Canister Purge Hose Ports
22) Check IAC Solenoid Function Start engine and allow to idle. Ensure transmission is in Park or Neutral and engine is warmed to normal operating temperature. Disconnect IAC solenoid wiring harness connector. If engine speed drops, go to next step. If engine speed does not drop, check throttle body for damage. If throttle body is okay, replace IAC solenoid and repeat QUICK TEST.
23) Check IAC Circuit For Short To Ground Turn ignition off. Disconnect scan tester from DLC. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 83 (IAC) and test pins No. 51 and 103 (PWR GND) at breakout box. If resistance is more than 10,000 ohms and idle speed is normal, go to step 30). If resistance is more than 10,000 ohms and high idle speed is present, replace PCM and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair circuit short to ground and repeat QUICK TEST.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 25). No test procedures have been omitted.
25) DTC P1505: Check Inlet Air Supply DTC P1505 indicates that IAC system has reached the adaptive learning limit. Possible causes are as follows:
? Air intake leaks or restrictions.
? Throttle body linkage binding.
? Contaminated or damaged IAC valve assembly.
? Damaged throttle body.
Inspect air intake system for leaks. Repair or replace as necessary. If air intake system is okay, go to next step.
26) Check Air Inlet System Turn ignition off. Remove air filter. Inspect air filter, MAF sensor and air inlet system for excessive dirt or contamination. Repair or replace as necessary and repeat QUICK TEST. If air filter is okay, go to next step.
27) Check Throttle Body Leave ignition off. Disconnect accelerator cable and air cleaner tube from throttle body. Check cable and throttle body linkage for binding or interference. If faults are present, go to step 3) under CIRCUIT TEST HU. If no faults are present, go to step 8) under CIRCUIT TEST HU.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 30). No test procedures have been omitted.
30) Check IAC System For Intermittent Open Or Short Circuit Connect scan tester to DLC. Ensure all accessories are off and engine is warmed to normal operating temperature. Turn

ignition on. Access IAC PID and RPM PID. IAC duty cycle should be 20-45 percent. Observe IAC PID and RPM PID for indication of fault while wiggling and bending wiring harness between IAC solenoid and PCM. Fault will be indicated by sudden change in IAC PID or RPM PID value. If any faults are found, isolate and repair as necessary. Repeat QUICK TEST. If no faults are found, problem cannot be duplicated at this time.

9/4/2008
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