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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.


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Mr Ludel,


   Thank you for posting this data! I had to move suddenly when my 90 yj was in the middle of a rebuild. I moved from Columbus Ohio area to Aspen Co! My brother back in Ohio has my jeep back together and is fighting some gremlins. I hope this helps him out. Have a good day!


Matt Ott

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