Can't pull Key On Engine Running (KOER) codes??

[byson1]

Engine is a 93 5.0 HO MAF from a 93 Mercury Cougar. Everything is OE and I reused to OE wiring harness from the cougar into the Bronco-ran fine for years. Recent running problems has me checking codes. I did not rewire the OE check engine light so I'm using a jumper wire (from Self Test Input to terminal 2 of Self Test Output) AND a small indicator light from terminal #4 of the STO to pos side of battery to do the test. I can successfully pull Key on engine off (KOEO) codes but after I pull those, wait 10 seconds and start the engine for the Key on engine running (KOER) codes I get nothing. No 4 flashes (indicating a V8) or anything else. I even tried grounding the Self Test Input (STI) to see if that would help but sill nothing. That did still allow me to pull the KOEO codes but not the KOER codes. Any ideas??

 

[mattt]

I always cycle the key off-on between KOEO & KOER tests. I've never tried to run them both with 1 key on cycle. Try that and see if it works.

 

[byson1]

Matt I actually did shut the ignition off for 10 seconds after
KOEO codes got through flashing. Then when I started the engine I would get nothing. Thanks

 

[byson1]

I'd be open to educated guesses It seems strange I can get codes while the engine is off but not while it's running.

 

[EFI Guy]

That isn't something I have ever encountered, but I found this:




My only other thought is that it may want to see a signal indicating neutral or park while trying to do a KOER test. But, usually it will just toss a code if you aren't in neutral / park.

 

[byson1]

Thanks EFI guy I'll check the O2. It's also possible the computer isn't reading neutral or park. My Bronco is a manual tranny and the computer came from an automatic. Not sure wht I did with the safety
wires-I'm sure they're buried somwhere in the harness.