yo JAKE,
ok
You have a 90, Bronco, correct?
If so and you can take time to electrically and visually troubleshoot w/ digital multimeter;
run a ground wire from Scan Tool or from the DLC "Self Test Input" to Battery Negative Post
This will replace what JOE Describes as; Put the jumper wire as indicated between "Self Test Input" and "Signal Return� Ground"
This is in case that "Signal Return� Ground" circuit is damaged or a bad ground (usually @
for Scan Tool grounding
by Jeremy M (Big '92, jermil01)
================
Next Set of troubleshooting;
NO CODES Troubleshooting by Ryan M (Fireguy50) at http://oldfuelinjection.com/?p=44'>http://oldfuelinjection.com/?p=44
http://oldfuelinjection.com/?p=44
excerpts;
Check Battery voltage, must be above 10.5 volts.
•Replace battery if not.
•Check battery connections, corrosion, ground faults, and wiring.
• Fix all wiring.
•Check alternator output, must be between 13.5 and 14.5 volts.
•Replace Alternator if not.
•Any recent voltage irregularities from electrical charging system can cause failures.
Check EEC relay, must show battery voltage when engaged.
•Replace relay and damaged wiring if not.
•Make sure pin 30 on the computer is hooked up correctly.
•Manual transmission computers need to sense SIG-RTN on pin 30 when in neutral.
•Automatic transmission computers need to sense Ground on pin 30 when in neutral.
READ MORE
to help go thru the steps;
Here is Ryans EEC IV PIN LEGEND
http://oldfuelinjection.com/truckpinouts.html
& EEC IV Connector Pin Outs
http://fullsizebronco.com/forum/attachment.php?attachmentid=17644&stc=1&d=1313769200