Here is 1987-90 Jeep YJ Wrangler and Jeep XJ Cherokee/MJ Comanche 2.5L TBI diagnostics information in PDF form. The first document includes all sensor and switch tests plus adjustments that affect engine tune, idle and reliability. Wiring schematics and ECU pin locations, test plugs and diagnostics included.
Jeep 2.5L TBI Complete Diagnostics-Sensors-Switches.pdf
Jeep 2.5L TBI ECU Inputs and Outputs.pdf
Jeep 2.5L TBI MAP Sensor Test.pdf
Jeep 2.5L Timing Chain and Tensioner.pdf
Jeep 2.5L Valve Timing Check.pdf
Jeep YJ 2.5L TBI Sensors and Pinout.pdf
YJ Wrangler 2.5L TBI Wiring of WOT to ECU.pdf
Jeep YJ 2.5L ISA Wiring Diagram.pdf
1987-90 2.5L TBI Intake Manifold and Sensors.pdf
1987-90 YJ Wrangler 2.5L TBI Emissions System Parts.pdf
YJ Wrangler Fuel Filter and Guard.pdf
2.5L TBI ISA Motor Adjustment.pdf
Used in conjunction with the many forum exchanges (search under "All Content" and "2.5L TBI" in the search box), plus the Jeep 2.5L TBI troubleshooting article at the magazine website, this information will help solve your Jeep YJ Wrangler or XJ Cherokee 2.5L TBI troubles. In references, the Model 81 is the Jeep YJ Wrangler. The Model 60/70 is the XJ Cherokee and MJ Comanche Pickup.
Moses