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Discussion Starter #1
i have this weird thing where my bronco will pull codes on its own, i dont have the sti grounded and it will still start codes, has anyone have this or know why?
 

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Never had that happen, so what codes does it display?
 

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Discussion Starter #4
it shows 33, even right after i clear it 33 is always shown, i dont have the wire grounded. i got out the volt meter out and the wire isnt grounded so i quess it is something to do with the computer?
 

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Discussion Starter #6
what i thought was code 33 is a system pass code i think, i didnt know that being a 94 it had 3 digit codes
 

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Discussion Starter #8
i found this in steve83's codes writeup i think it might be whats happening

4) Grounded STO/MIL Circuit
The processor controls the MIL by grounding the STO/MIL circuit (Pin 17). If this circuit shorts to ground, whether the processor is controlling it or not, the MIL will be lit. Starting in 1991, if the processor has lit the MIL, it will hold it on for a minimum of 10 seconds. If the MIL flashes quickly, the concern is probably the STO/MIL circuit shorting intermittently to ground.

so ill check the STO/MIL wires, STO is self test output but does anyone know what MIL is? thanks for the help
 

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Satyr of the Midwest
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You cannot POSSIBLY have a code 33. Your 1994MY will only output three-digit codes, so you're likely misreading the output; it's probably code 111, meaning no DTCs present.

Just because you're not deliberately grounding the STO doesn't mean that the STO line isn't connected to ground elsewhere. I'd inspect the harness, starting at the EEC TEST connector, and work my way back down to the PCM. These trucks have a known problem in their harness in that specific area, but most of the time that will entail a PIP malfunction, causing stalling, bucking, no-start, etc.

MIL == malfunction indicator lamp == check engine light
 

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Discussion Starter #10
i found this in another thread

Also; other issues that affect the PSOM are
TSB 95-5-21 Fuse "E" Inoperative - ABS Light On - Back-Up Lamps Inoperative - DRLs Inoperative - MIL On - Speedometer Inoperative
Publication Date: MARCH 13, 1995
LIGHT TRUCK: 1992-1995 BRONCO, F-150-350 SERIES
ISSUE: On some vehicles the HO2S wires in the 12A690 (subassembly of the 14B060 battery cable) harness may become chafed and the vehicle could exhibit any one of the following conditions:
ABS light on
Speedometer inoperative
Back-up lamps inoperative
Daytime running lamps inoperative
Trailer battery charge relay inoperative
MIL on, displaying Codes: 172, 173 or 41 for HO2S failure
Inadvertent PCM Self-Test

if i pull fuse E it stops pulling codes, so i think my HO2 harness may be chaffed and causing it to pull codes.
 

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Wow great find! So now you can attach a DVM with the fuse pulled, check for path to ground. Good luck.
 

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Discussion Starter #12
i unpluged the HO2 sensor harness by the headlight and its stopped. plug it back in and it started doing it again so its definetly in the HO2 sensor harness. ill probably get some battery cables made and find the short then
 

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Satyr of the Midwest
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Some electrical tape might work in the mean time. ;)
 

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Discussion Starter #14
im probably getting them made in the next few days if not tomorrow, it'll be easier to find the short with them out:thumbup
 

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Discussion Starter #15
it was the HO2 sensor harness, down where it plugs into the O2 sensor some of the wires were melted together,
also heres a pic of my new battery cables. they're made with 2ga welding cable, a shop made them for $41
 
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