Diode on speed density IAB but not MAF?

[AaronATX]

Something I just noticed the last few days of screwing with my friends 93lx..

Seems like all MAF 5.0 wiring harnesses have NO diode wired into the IAB motor. All the speed density ones do..... anyone have a clue as to why this is?

[anthonydalrymple]

If i were tro hazard a wild haired guess; I'd think it was because the '88 California-up EEC's have some type of internal protection the earlier EEC's didn't. Again, this is a wild haired guess & a TTT fer 'ya....

[wbrockstar]

All 86-88 SD equipped Foxbodys had a diode wired into the iac harness because the iac valve itself for this year range was not equipped with a diode.Once the 89-93 were manufactured, the diode was left out of the iac harness and the diode was built into the iac valve itself.So long story short:

86-88= iac harness diode + iac valve with no diode
89-93= iac harness with no diode + iac valve with built in diode
All remanufactured iac valves also come equipped with the diode too

So if you're gonna use a 89-93 or remanufactured iac valve on a 86-88 SD Foxbody with its original iac harness that included the diode,cut the diode out of the iac harness wires and splice the red wires back together.Cover the splice & the cover the w/lt blue wire with heatshrink tubing.