Iron Weasel, that's great info. I also have a '94 EB. Any info on codes 17,22,23,24,25,26?
17 - Reference Voltage
Code 17 is generated by the ECU indicating a loss of system reference voltage.
POSSIBLE CONTRIBUTING COMPONENT/VEHICLE WIRING FAULTS
* 30 amp fuse open
* Intermittent connections to battery, main relay or ground
* Main relay coil or contacts open
* Open or short to ground in Circuit 532 (O/Y)
* Open or short to ground in Circuit 599 (PK/LG)
* Open or short to ground in Circuit 601 (LB/PK)
* Short to ground through valve block
* Intermittent valve failures
* High resistance valves
If Code(s) 22, 23, 24, 25, 26, or 27 have also been obtained along with Code 17, an intermittent valve or valve wiring fault is indicated.
* Disconnect the 8-pin connector from the HCU.
* Measure resistance between the following on the component side of the 8-way:
NOTE: Refer to the above Mini-Schematic for valve block pin designations.
* Pin 1, Pin 4 and Pin 2 - (RA Inlet)
* Pin 1, Pin 4 and Pin 3 - (RA Outlet)
* Pin 1, Pin 4 and Pin 5 - (FR Outlet)
* Pin 1, Pin 4 and Pin 6 - (FL Inlet)
* Pin 1, Pin 4 and Pin 7 - (FL Outlet)
* Pin 1, Pin 4 and Pin 8 - (FR Inlet)
* All inlet valves should be 5-8 ohms .
* All outlet valves should be 3-6 ohms . A drive over rough road is recommended while the resistance is being monitored.
NOTE: Valve resistances causing this problem tend to fluctuate rapidly. Another person to monitor resistance while the first drives is highly recommended.
* Does the resistance on any valve move out of specification at any time?
YES -- High or low valve resistance detected. Replace HCU.
NO --
* Measure resistance between the following on the component side of the HCU 8-pin connector:
* Pin 1 and valve block.
* Pin 4 and valve block.
* A drive over rough road is recommended while the resistance is being monitored.
NOTE: Valve resistances causing this problem tend to fluctuate rapidly. Another person to monitor resistance while the first drives is highly recommended.
* Is the resistance measured less than 10M ohms at any time?
YES -- Replace HCU.
NO --
* Jumper Breakout Box Pin 19 to Pin 1 or Pin 14.
* Set up DVOM to measure voltage between Breakout Box Pins 17 and Pin 1 or Pin 14.
* A drive over rough road is recommended while the voltage is being monitored.
* Does the voltage fall below 9.5V at any time?
YES -- Find and Repair source of high resistance or open in one of the following: Circuit 532 (O/Y) between HCU and System Relay. Circuit 537 (T/Y) between battery and System Relay.
NO -- Conclude Intermittent Diagnosis
EDIT:
While the most likely problem is the HCU took a dive on you, you should still check out the wiring just to rule it out. I checked a few places to see how much a new Hydraulic Control Unit (HCU) will run, and for a re-manufactured unit, you're looking at almost $1,000 from Rockauto. If you need any additional diagrams or pin-outs, let me know and I'll get them to you ASAP.