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Vehicle info:
-95' bronco with a 97 7.3L and zf5 in it
-Dash harness modified to accommodate the rear window switch instead of the fuel selector.
-Under hood harness from a 95? Missing the relays next to the distribution box/fuse box.
-has 2 mystery plugs too but that's not a concern
- Computer I think is from a 94.5 manual
Issues:
Check engine light is on, but I cannot get a scan tool to connect to it. Has power along with the cigarette lighter. Can't find schematics and most Google searches come to super duty trucks not OBS. They say pin 4 should have no resistance to ground; I have 458 ohms. No idea where to go from here.
Second issue, dead throttle pedal. No response from it, haven't checked for power or ground with it, but it's another issue none the less and want it mentioned.
Any ideas where to start with the reader? Have used a Bluetooth one and my car gauge pro app as well as a blue point scan tool. Neither will connect only receive power.
Found out my scanner doesn't work in the daily anymore so obviously it doesn't work in this.
Swapped the pedal into the daily.. functions as it should, still doesn't work in the bronco.
Swapped the PCM from the daily into the bronco and pedal doesn't work.
Fixed the p/s engine/frame ground, no changes.
Blew the idle fuse so have to replace that before further troubleshooting the pedal.
Fuel gauge:
Redid the float arm on the sending unit. Used a jumper wire on the body harness and it sunk the gauge to empty. Tested the signal wire from the gauge to the connector, no issues. Also checked the sensing unit for proper resistance and different fill levels with no issues. However when I plug it all up the fuel gauge goes all the way past full. Further investigation required.
Here is a diagram showing the fuel electrical system. The yellow wire at center left goes to the actual fuel gauge. I believe 22 ohms is empty and around 55 ohms is full, but going from memory. If the gauge is going past full with everything hooked up and you know there is less fuel in the tank then it sounds like a bad connection somewhere, high resistance. Could be the switching valve itself as it has relay type contacts inside there as the diagram indicates.
Idle circuit needs 12 volts on the IVS switch. Without it the peddle won't work. That fuse protects other items also so I'll look at the diagram and report back.
Could be the switching valve itself as it has relay type contacts inside there as the diagram indicates.
Idle circuit needs 12 volts on the IVS switch. Without it the peddle won't work. That fuse protects other items also so I'll look at the diagram and report back.
Doesn't have a switching valve, it's a bronco with a single tank. Put the rear window switch in it's placed and cut out the switch.
I'll double check my volts at the pedal. Been trying to use alldata for troubleshooting.
The IVS switch has two wires plugged into it. One wire will have 12 volts on it with key in run position. The other wire will measure zero volts with the peddle not pushed. When pressing the peddle the switch will close causing the PCM to see you are pressing on it and allows the TPS to be recognized by the computer.
IVS switch is protected by fuse #3, 3 amp. Guess it's the same for the Bronco, don't know for a fact though.
All the wiring is from a F-SERIES 7.3 truck except the body harness so yes that's true. I get volts to the switch key on but can't probe into the back of the switch to check volts as the throttle moves. I have however jumped the plug (as some say you can if the IVS is faulty) and no change.
Going to be ordering an EVTM for the bronco and a 97 F350 so wiring can be diagnosed better/easier. As well as finding a new dash harness because this one is kind of suspect to me.
Well the fuel gauge was just... Corroded plug on the body harness side. Stuck a drill bit in there, turned it by hand, dielectric grease, and now it works.
Pedal is still a mystery. Ordered EVTMs for 95 bronco and 97 F350 so that's 2 weeks out but got this from today.
Well after some attempts at trying to understand the alldata troubleshooting for my pedal not working I have gone through this (mind you I can't read codes so I'm guessing on codes):
High input troubleshooting led to "replace PCM" (used PCM from my truck, no change. Pedal from bronco in my truck works).
Low input troubleshooting has closed me off at "open in ground on circuit 837" because I do not have "less than 5 ohms" because I have 89 ohms (provided I checked the right wire and I think I did). So without an actual schematic, I can't do much more until my EVTMs arrive
So yesterday I pulled the dash harness out to inspect it and ohm some wires out for the pedal.
1) found a mystery brown plug behind the aluminum piece on the driver side that is not plugged in to anything.
2) the dash harness has less that .3 ohms for all pedal wires.
So I found the matching wires on the engine bay harness and ohm'd them out. One had .3 while the other 2 had well over 300k ohms. I checked this against the pedal in my truck.
Outside wires have less than 1 ohm while center wire has over 300k ohms.
Cleaned up all the grounds in the engine bay as well as all the plugs and cleaned some green goop out of them. Still have high resistance to both ground and the corresponding plug wires at the PCM from the firewall plug.
I feel there is potential damage inside engine harness and might have to pull or replace it. I might replace it as it seems to be missing some plugs anyways.
