Parts for your 1991 Toyota Hilux surf-Throttle position sensors

1991 Toyota Hilux Surf throttle-position-sensor (TPS): what it does and how to look after it

Based on Toyota factory repair manuals for the 22R‑E and 3VZ‑E EFI petrol engines (Engine Control – EFI sections), the Toyota 2L‑TE Engine Repair Manual for the turbo‑diesel, and the 1991–1992 Toyota Hilux/4Runner Electrical Wiring Diagram, the 1991 Hilux Surf is fitted with a throttle‑position sensor. On EFI petrol models it’s mounted on the throttle body, providing IDL and VTA signals to the ECU. On the 2L‑TE diesel it’s fitted to the injection pump throttle lever (often called an accelerator/TPS sensor) and is used by the ECU for fuelling, timing and EGR control. The Haynes 4Runner/Pick‑up 1989–1995 manual documents the same arrangement.

On a 1991 Hilux Surf, the TPS tells the ECU exactly how far and how fast the throttle is being opened. That little signal is a big deal: it sharpens tip‑in response, trims fuelling, helps set ignition timing on petrol engines, and influences auto shift timing. On 2L‑TE diesels it also guides timing advance, smoke control and EGR behaviour. When the idle switch inside the TPS says “closed”, the ECU manages idle speed and decel fuel cut cleanly.

There’s no fixed replacement interval, but checking the TPS every 40–60,000 kilometres as part of a routine service is smart. A crook TPS can cause off‑idle flat spots, surging, hunting idle, harsh or late shifts in autos, poor economy, and a check‑engine light (commonly code 41 on Toyota ECUs). Under the bonnet, make sure the connector is clean, the harness isn’t chafed, and the throttle plate or pump lever returns to its stop freely.

Adjustment and testing are straightforward with a multimeter. With ignition on, the VTA signal should sweep smoothly from roughly 0.5 V at closed throttle to around 3.5–4.5 V at wide‑open, without drop‑outs. The idle contacts (IDL–E2) should have continuity at closed throttle and open just off idle per the manual’s feeler‑gauge spec. If replacing the sensor: disconnect the battery, mark the old position, use the right JIS screwdriver or a small impact driver to crack the factory screws, fit the new unit, then set the idle switch and VTA voltage as specified. Torque the screws lightly and don’t force the rotor. On 2L‑TE pumps, ensure the lever returns to the stop and don’t disturb pump timing. Finish by clearing ECU memory (pull the EFI fuse for a minute), then road‑test for smooth take‑off and clean shifts. Easy as.

• Common symptoms: hesitation off idle, erratic idle, harsh/late auto shifts, CEL code 41, poor fuel use.
• Service tip: clean the connector, check earths, and verify a smooth VTA voltage sweep.

Does a 2L‑TE diesel Surf actually have a TPS?
Yes. Toyota’s 2L‑TE uses an accelerator/TPS on the injection pump to inform the ECU of driver demand. It’s critical for timing advance, fuelling transitions and EGR control, even though a diesel doesn’t rely on a throttle plate like a petrol does.

Can you drive with a dodgy TPS?
Usually, but it’s not ideal. You may get flat spots, harsh shifts and higher fuel use. Prolonged driving can foul plugs on petrols or stress the auto. Testing and adjustment often fix it, if the signal is jumpy, replacement is the go.

How hard is TPS adjustment at home?
With a multimeter and feeler gauges it’s quite doable. Follow the factory specs for IDL switch clearance and target voltages. Take care with the small screws and always recheck idle and off‑idle response after a short drive.