Parts for your 2002 Daihatsu Gran move-Temperature sensors

2002 Daihatsu Gran Move temperature sensors — what they do and how to look after them

Temperature sensors are absolutely used on the 2002 Daihatsu Gran Move (also sold as the Pyzar). Factory technical literature for the G303/G313 series — including the Daihatsu Gran Move/Pyzar Workshop Manual (1997–2002), the Daihatsu/Toyota Electronic Parts Catalogue, and common service data providers used in AU/NZ workshops — all list an engine coolant temperature (ECT) sensor for the ECU, a separate sender for the dash gauge, and an intake air temperature (IAT) sensor (often integrated with the intake manifold pressure/air metering setup). Many markets for this model also use the ECT signal for radiator fan control via the ECU and fan relay, some variants use a separate thermo switch on the radiator.

On this Gran Move, temperature sensors do the quiet heavy lifting that keeps the engine happy day to day. The ECT sensor tells the ECU how hot the engine is so it can tweak fuelling, ignition timing, idle speed, and cold‑start enrichment. The dash sender feeds the temp gauge so the driver can spot overheating early. The IAT sensor helps the ECU adjust mixture for the air coming in, improving economy and drivability across Aussie and Kiwi weather swings.

There’s no fixed replacement interval, but after two decades it’s common‑sense maintenance to check or replace suspect sensors, especially when doing a thermostat, radiator, or coolant service. Typical red flags include hard cold starts, rich running, high idle, poor fuel economy, a lazy or dead temp gauge, cooling fans not kicking in, or an engine light with a temperature‑related fault. A quick test is to compare a cold ECT reading on a scan tool to ambient — they should match. Inspect connectors for green corrosion, brittle wiring, or coolant weep past the sensor’s seal.

Replacement is straightforward: the ECT sensor usually lives on the thermostat housing or cylinder head, the dash sender is nearby, the IAT sits in or near the intake. Always depressurise the cooling system, catch and refill with the correct long‑life coolant, fit a new sealing washer/O‑ring, and torque to spec. Bleed out air so the sensor sees liquid, not bubbles. Sticking with quality OEM‑spec parts avoids erratic readings that can waste fuel or mask a genuine overheating issue.

• Keep coolant fresh and correct for the alloy engine.
• Clean electrical connectors and repair damaged looms.
• Consider preventative ECT replacement when doing the thermostat on higher‑kilometre cars.

Popular questions

Where is the coolant temperature sensor on a 2002 Daihatsu Gran Move?
It’s typically threaded into the thermostat housing or the cylinder head near the top radiator hose. On some variants, the ECU ECT sensor and the dash gauge sender sit side‑by‑side but have different connectors. A quick look from the left front of the engine bay usually spots them.

How can someone tell if a temp sensor is failing on a Gran Move?
Common clues are hard cold starts, rich fuel smell, erratic idle, poor economy, cooling fans running constantly or not at all, or a dead/peaky gauge. A scan tool showing unrealistic coolant temperature (e.g., reading 80–100°C stone cold) is a giveaway. Wiring and connector issues are just as common as the sensor itself.

Does the radiator fan use a separate switch or the ECU on the 2002 Gran Move?
Many late Gran Move/Pyzar models use the ECU to command the fan relay based on the ECT sensor. Some markets/years retained a separate thermo switch in the radiator tank. If unsure, check the local wiring diagram in the workshop manual or look for a two‑pin switch on the radiator.