Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Jeep Wrangler Laredo, AutomaticFACTORY OEM SERVICE PROCEDURE
Functional Test
- Disconnect wire connector at TPS. Check voltage at TPS connector pins "B" (ground) and "C" (5 volt supply) with key on. If there is not approximately 5 volts, turn key off. Check for continuity between ECU connector pin No. 16 and TPS connector terminal "C".
- If there is an open circuit, repair TPS wire harness power supply circuit between ECU and TPS and retest. If there is no open circuit, check for continuity between ECU connector pin No. 13 and pin "B" of TPS connector. If there is an open circuit, repair TPS wire harness ground circuit between ECU and TPS and retest.
- If there is no open circuit, check for continuity between ECU connector pin No. 31 and TPS connector pin "A". If there is an open circuit, repair TPS wire harness between ECU and TPS and retest. If there is no open circuit, replace ECU and retest.NOTE: DO NOT disconnect sensor wire harness connector. Insert voltmeter test leads through back of wire harness connector to make contact with sensor terminals. On some models, it may be necessary to remove throttle body from intake manifold to gain access to sensor wire.
- With wire connector still disconnected at TPS. Check voltage at TPS connector pins "B" (ground) and "C" (5 volt supply) with key on. If there is approximately 5 volts, connect TPS wire connector to TPS. Check voltage at TPS connector terminals "A" (+) and "B" (ground) with key on and throttle plate wide open.
- If output voltage is 4.6-4.7 volts, TPS switch and adjustment are okay. If voltage is not correct, adjust voltage to specification. If voltage can be adjusted to 4.6-4.7 volts at WOT, TPS and wiring are okay. If voltage cannot be adjusted to specification, replace TPS and adjust voltage.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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