LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Jeep >> 1990 >> Wagoneer >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 4.0L >> Electronic Control Unit (Ecu) >> Ground Circuits
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Ground Circuits

  1. Using an ohmmeter, check for continuity to ground on ECU ground terminals. See ECU GROUND CIRCUITS table. Resistance should be zero ohms. If not, repair open ground circuit.
  2. Using a DVOM, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. See ECU GROUND CIRCUITS table. With vehicle running, voltmeter reading should be less than .1 volt. If voltmeter reading is greater than .1 volt, check for open, corrosion or loose connection on ground lead.
ECU GROUND CIRCUITS

Application ECU Terminals
4.0L B-11 & B-12