2003 Mitsubishi Eclipse Jump started car backwards

Have you looked at the temperature sender? It's screwed into the the block on the back side at the water outlet.

Yoiu may have fried the instrument panel. Or the wiring to it. INSPECTION PROCEDURE 4: Engine Coolant Temperature Gauge does not Work Fig. 147: Inspection Procedure 4: Engine Coolant Temperature Gauge Circuit Diagram Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. Fig. 148: Inspection Procedure 4 Engine Coolant Temperature Gauge Circuit Component Locations Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. CIRCUIT OPERATION à   The ignition switch (IG1) circuit is the power source for the engine coolant temperature gauge. à   Resistance value, which the engine coolant temperature gauge units sends to the combination meter, is dependent on temperature of the engine coolant. This causes circuit current to fluctuate. à   The engine coolant temperature gauge moves the needle according to the circuit current. TECHNICAL DESCRIPTION (COMMENT) If the ignition switch (IG1) circuit is open, the gauge needle will not move at all. If the ground circuit is open, the gauge needle will move up to its extreme position. TROUBLESHOOTING à   Malfunction of the engine coolant temperature gauge unit à   Malfunction of the combination meter (printed-circuit board or engine coolant temperature gauge assembly) à   Damaged wiring harness or connectors DIAGNOSIS Required Special Tool: MB991223: Harness Set STEP 1. Check the speedometer operation. Q: Does the speedometer work normally? YES: Go to Step 2. NO: Refer to INSPECTION PROCEDURE 1: Speedometer does not Work. STEP 2. Check the engine coolant temperature sensor signal circuit at the engine coolant temperature sensor connector B-08 by back probing. 1. Do not disconnect the engine coolant temperature sensor connector B-08. 2. Turn the ignition switch to "ON" position. 3. Measure the voltage between terminal 1 and ground by back probing. Page 1 of 3 COMBINATION METER & SPEED SENSOR -2003 Mitsubishi Eclipse GS 8/28/2008
à   The measured value should be approximately 9 volts or more. Fig. 149: Checking Engine Coolant Temperature Sensor Signal Circuit Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. Q: Does the measured voltage correspond with this range? YES: Go to Step 5. NO: Go to Step 3. STEP 3. Check the engine coolant temperature sensor connector B-08 and combination meter connector C-43 for damage. Q: Are engine coolant temperature sensor connector B-08 and combination meter connector C-43 in good condition? YES: Go to Step 4. NO: Repair or replace the connector. The engine coolant temperature gauge should work normally. Fig. 150: Identifying Engine Coolant Temperature Sensor Connector B-08 Location (2.4L Engine) Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. Fig. 151: Identifying Engine Coolant Temperature Sensor Connector B-08 Location (3.0L Engine W/O Variable Induction System) Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. Fig. 152: Identifying Combination Meter Connector C-43 Location And Terminal View Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. STEP 4. Check the wiring harness between engine coolant temperature sensor connector B- 08 (terminal 1) and combination meter connector C-43 (terminal 3).
NOTE: After checking intermediate connector C-28, check the wire. If intermediate connector C-28 is damaged, repair or replace it. Q: Are the wiring harness between engine coolant temperature sensor connector B-08 (terminal 1) and combination meter connector C-43 (terminal 3) in good condition? YES: Repair or replace the combination meter (printed-circuit board or engine coolant temperature gauge assembly). The engine coolant temperature gauge should work normally. NO: Repair or replace the connector. The engine coolant temperature gauge should work normally. Fig. 156: Identifying Intermediate Connector C-28 Location Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. STEP 5. Check the engine coolant temperature gauge unit. 1. Drain the engine coolant. ENGINE COOLING. 2. Remove the engine coolant temperature gauge unit. 3. Immerse the unit in 70 °C (158 °F) water to measure the resistance. Fig. 157: Checking Engine Coolant Temperature Gauge Unit Courtesy of MITSUBISHI MOTOR SALES OF AMERICA. Q: Is the resistance 104 +/- 13.5 ohms? YES: Repair or replace the combination meter (printed-circuit board or engine coolant temperature gauge assembly). The engine coolant temperature gauge should work normally. NO: Replace the engine coolant temperature gauge unit. The engine coolant temperature gauge should work normally.