Parts for your 1999 Mitsubishi Pajero-Throttle position sensors

1999 Mitsubishi Pajero throttle position sensor: purpose, checks, and replacement

Based on factory documentation, the 1999 Mitsubishi Pajero does use a throttle position sensor (TPS) on petrol engines and an accelerator position sensor (APS, functionally a TPS) on the 2.8‑litre 4M40 diesel injection pump. This is detailed in the Mitsubishi Pajero/Montero Workshop Manual (Engine Electrical sections for 6G72/6G74 and Diesel Control for 4M40), and echoed in the Mitsubishi ASA electronic parts catalogue for 1999 models. Independent manuals such as the Haynes Pajero/Montero guide also reference TPS/APS usage for fuelling, ignition, and transmission control. So, for a 1999 Pajero—whether V6 petrol or electronically managed diesel—a throttle-position-type sensor is relevant and fitted.

What does it do? On the petrol V6, the TPS tracks throttle plate angle so the ECU can trim fuel, set ignition timing, manage idle control, and coordinate automatic shift behaviour. On the 4M40 diesel, the APS on the pump reports driver demand to the ECU for timing, EGR and smoke control, and to tidy up idle and off‑idle response. A healthy sensor keeps throttle feel smooth, shifts consistent, emissions in check, and fuel use sensible across Aussie and Kiwi conditions.

Common signs the TPS/APS is on the way out include a check engine light, flat spots on take‑off, erratic idle, hunting at cruise, harsh or delayed auto shifts, and higher than usual fuel consumption. Under the bonnet, poor connections or a cracked harness near the throttle body or pump are frequent culprits.

• Servicing tips: During routine servicing, inspect the connector and loom for corrosion, stretched wires, or oil ingress. Clean the throttle body on petrol models without flooding the sensor.
• Testing: With a multimeter back‑probe, look for a smooth voltage sweep (roughly about 0.4–0.7 V closed to ~4.0–4.5 V wide‑open on many petrol setups). Any dead spots or jumps suggest replacement.
• Adjustment: Many petrol TPS units are slotted for base‑voltage adjustment, set per the workshop manual, ideally with a scan tool watching throttle angle and the idle switch flag. The 4M40 pump‑mounted APS is set by voltage at a specified throttle lever position—avoid moving the pump linkage beyond spec.
• Replacement: Disconnect the battery, mark the old sensor’s position, and avoid forcing the sensor shaft. Fit the new unit, nip the screws to spec, then carry out throttle/idle relearn if applicable.

Quality OEM‑equivalent parts tend to last and behave better. After replacement, a short test drive over varied speeds and a few kilometres will confirm smooth throttle and tidy shifts.

FAQs

Does a 1999 Mitsubishi Pajero have a throttle position sensor?
Yes. Petrol V6 models have a TPS on the throttle body, 2.8‑litre 4M40 diesels use an APS on the injection pump that serves the same role for the ECU. This is documented in Mitsubishi’s workshop manual and parts catalogue for the 1999 Pajero.

What symptoms point to a bad TPS on a 1999 Pajero?
Expect flat spots, hesitation, erratic idle, a check engine light, higher fuel use, and, on autos, harsh or inconsistent shifts. Wiring faults at the connector can mimic a failed sensor, so rule those out first.

Does the TPS need programming after replacement?
Most petrol sensors only need a base‑voltage adjustment and an ECU idle/throttle relearn. The 4M40 diesel’s APS is set by voltage on the pump lever—no programming, just correct mechanical adjustment. A scan tool makes the job quicker and more accurate.