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5.0L (1979-1995) MustangTechnical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.
**Special Note**
If you ever have to replace the iac valve for any reason,be aware that all remanufactured iac valves available for sale come with the diode built into them,regardless of which year model part you ask for at the parts counter.
IOW- if you go to Autozone to buy an iac & tell them you need one for a 86 Mustang,youll be given a iac with the built in diode.If you install a diode equipped iac valve on a 86-88 Mustang,with the diode equipped iac harness still in place,idle/surging/ stalling issues will usually occur.
A tsb was issued years ago for this exact problem.Theres a easy fix for this issue.Just remove the diode from your harness.
REMOVAL STEPS:
The diode has two red wires on one side & one lt blue/white wire on the
other side.Cut both red wires at the diode,splice them together with solder & cover with heat shrink tubing.Cut the lt blue/white wire at the diode & cover its exposed end with heat shrink tubing.Finished...... The diode is shown in the picture below.
Last edited by wbrockstar; 01-09-2019 at 07:19 PM.
If you purchase a remanufactured iac valve (all have a diode) or get one off of a 89+ model (all have a diode),yes youll wanna delete the harness diode.If the iac doesn't have a diode,leave the harness diode alone.Im not sure if Ford or online sellers of oem Ford parts have the iac w the diode or not so check that before buying.The plastic portion of the iac where you plug the harness in will usually have the letter "D" embossed in it,like the diagram below,if it has a diode built in to it.Another way to check it is by disconnecting the harness and using a multimeter on the iac.Set the meter to read ohms.Touch the red meter lead to one iac terminal & touch the black meter lead to the other iac terminal,take a reading.Now reverse the meter leads on the iac terminals,take another reading.One reading should show 7-13 ohms or a similar range.The other reading should show a very high ohms value,OL or Infinity.If your readings appear like the values above, this indicates the iac valve does indeed have a diode inside it.If you get the same ohm reading regardless of which way the meter leads are connected to the iac terminals,the iac has no diode.
Heres a really great thread that goes into great detail about the issues caused by the diode and the removal process. http://vb.foureyedpride.com/showthre...ng-Idle-SOLVED
Last edited by wbrockstar; 01-10-2019 at 01:45 PM.
01-09-2019, 07:12 PM
