Cherokee 2WD L6-242 4.0L VIN M FI (1987)
3.
With ignition switch in the On position, check MAP sensor supply voltage at MAP electrical connector C. Voltage reading should be 4.5 to 5.5
volts. If voltage is not as indicated, check for voltage reading of 4.5 to 5.5 volts at ECU electrical connector terminal C-14 to ensure wiring is
satisfactory. If wiring is satisfactory, check ECU with diagnostic tester M.S. 1700.
4.
Using an ohmmeter, check MAP sensor ground circuit at sensor connector terminal A and ECU connector terminal D-3. Repair wiring a
necessary, if continuity does not exist. If wiring is satisfactory, but continuity does not exist proceed to step 5.
5.
Check MAP sensor ground circuit at ECU, by connecting an ohmmeter between ECU electrical terminals D-3 and B-11. If continuity does not
exist, check for defective ground wire connection at right hand side of cylinder block. If ground is connection is satisfactory, replace ECU. If
terminals D-3 is shorted to 12 volts, correct this condition before installing replacement ECU.
