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Mazda3 2003-2008 factory workshop and repair manual download

Summary (what this guide does)
- Explains what the throttle position sensor (TPS) is, why and when to repair it on a Mazda3, how the system works, and what can go wrong.
- Step‑by‑step diagnostic checks, removal/installation, and post‑repair checks written for a beginner mechanic.
- Includes components, tools, safety, common pitfalls, and analogies to make the electronics/feedback concept easy to understand.

Important model note up front
- Mazda3 TPM/TPS implementations vary by year and engine. Older cars often have a separate TPS on the throttle body shaft. Most modern Mazda3 use an electronic throttle body where the TPS is integrated with the throttle body assembly and is not sold separately. Before you start, check a repair manual or parts catalog for your exact year/engine to know whether you can replace a separate TPS or must replace the whole throttle body assembly.

Basic theory — why this repair is needed and how the system works (analogy)
- Role: The TPS tells the engine control module (ECM/PCM) how far the throttle plate is open. The ECM uses that information (plus input from the accelerator pedal position sensor) to decide fuel injection, ignition timing, idle control and throttle motor position.
- Analogy: Think of the TPS as the “needle” on a speedometer telling the car how open the air door is. If the needle lies or jumps, the engine “thinks” the door is open more or less than it actually is, so the ECM makes the wrong fuel/air adjustments — idle surges, hesitation, stalling, or a check engine light result.
- How it works electrically: Most TPS units are 3‑wire devices: a 5V reference from the ECM, a ground, and a variable signal back to the ECM. As the throttle shaft turns, the TPS (a variable resistor or Hall sensor) changes the signal voltage smoothly from about 0.5 V (closed) up toward ~4.5 V (wide open), or in some digital modules it sends a digital reading. The ECM expects a smooth, predictable change. Sudden drops, jumps, or no signal cause trouble codes (P0120–P0124 family, and sometimes drive‑by‑wire codes).
- Why needed: Wear, contamination, wiring damage, or internal failure can give incorrect voltage/feedback, causing drivability problems.

Key components (what each one is and does)
- Throttle body: Contains the throttle plate (butterfly) and houses the TPS on older designs; on modern designs also contains the throttle motor (actuator) and integrated sensors.
- TPS (throttle position sensor): Senses throttle shaft angle; provides analog (or digital) signal to ECM.
- Accelerator pedal position (APP) sensor: Located at the pedal — the driver’s demand. On modern cars APP is the primary input; the TPS is feedback. ECM compares APP and TPS to detect discrepancies.
- ECM/PCM: Receives sensor signals, calculates fuel/air and throttle motor commands, stores DTCs (diagnostic trouble codes).
- Wiring harness and connector: Carries 5V, ground and signal; corrosion, broken wires, or poor pins cause errors.
- Intake hose and MAF/MAF sensor (if equipped): Not TPS parts but often removed to access the throttle body and potential contamination sources.
- Throttle body gasket/seal: Between throttle body and manifold — replace if damaged.

Symptoms that point to a bad TPS
- Check engine light (CEL) with P0120–P0124 or related codes.
- Rough idle, stalling at idle, idle hunting.
- Hesitation, jerking, or poor throttle response when accelerating.
- Sudden surges in speed or uncommanded throttle behavior (on older systems).
- Limp mode or reduced power (drive‑by‑wire safety).
- Inconsistent/incorrect voltage seen at TPS connector.

Tools and supplies
- Basic hand tools: metric socket set, ratchet, extensions, screwdrivers (flat and Phillips), Torx or hex bits if needed.
- Multimeter (digital) to read voltage and continuity.
- OBD‑II scanner capable of reading live data and clearing codes (preferred). A simple code reader is helpful.
- Safety gloves, eye protection.
- Replacement TPS or throttle body assembly (confirm part number).
- New gasket if throttle body is removed.
- Contact cleaner or electronic cleaner (NOT carb cleaner directly on sensors).
- Torque wrench (helpful for correct bolt torque; if not available, snug to hand‑tight + 1/4 turn).
- Optional: dielectric grease for connector pins, small pick or brush for connector cleaning.

Safety first
- Work on a cool engine. Hot intake or throttle components can burn you.
- Disconnect the negative battery terminal if doing electrical work for more than a quick test; some relearn procedures require battery disconnect, but leaving battery connected allows scanning and live checks.
- Avoid contaminating the throttle body sensors with harsh chemicals.
- Be careful with the throttle plate; don’t force it or damage the shaft seal.

Diagnostics — verify before you replace
1) Read codes
- Plug in an OBD‑II scanner. Note stored/active codes and freeze frame. Codes like P0120–P0122 typically indicate TPS issues; P2100–P2138 can be drive‑by‑wire related.

2) Visual inspection
- Inspect the wiring harness and connector for corrosion, broken wires, pins pushed back, or melted insulation.
- Wiggle the harness while watching live data or CEL to see if wiring intermittent causes changes.

3) Clean throttle body (first simple fix)
- Carbon buildup around the throttle plate can cause poor readings. Remove intake hose, inspect and clean throttle plate with throttle body cleaner. Operate throttle (manually or with ignition on) to verify smooth movement.
- If you clean the throttle body and the problem persists, continue diagnostics.

4) Live data check with scanner
- Watch TPS signal (voltage/percent) while slowly opening and closing throttle. It should change smoothly and monotonically — no jumps or drops, no sudden returns to zero except closed. Compare APP sensor values vs TPS — they should track in proportion to each other.

5) Multimeter bench/at‑car tests (three‑wire sensor)
- Backprobe connector pins (refer to wiring diagram or identify wires: 5V ref, ground, signal). With ignition ON (engine off):
- Between reference pin and ground: ~5.0 V.
- Signal pin to ground: around 0.4–1.0 V at closed throttle, rising smoothly toward ~4.0–4.5 V at wide open.
- If reference voltage missing: wiring/ECM problem.
- If signal jumps, is noisy, sticks, or is open: sensor likely bad.

6) Resistance test (older, non‑powered check)
- If sensor is a potentiometer, measure resistance across outer terminals (fixed) and middle to each outer while turning shaft — should move smoothly without dead spots. (This is less used with modern digital sensors.)

Decide
- If wiring and reference voltage are good but signal is erratic or out of range, replace TPS (or throttle body if integrated).
- If wiring is bad, repair wiring/connectors first.

Removal and replacement (general steps — adapt to your exact Mazda3 year)
Note: Confirm whether TPS is separate or integrated. If integrated, you will replace the whole throttle body.

Preparation
- Park car on level ground, parking brake ON, engine cool.
- Disconnect negative battery terminal if you’ll be working the electrical connector for more than quick tests or if your repair manual recommends it.
- Remove air intake duct to access throttle body (usually loosen hose clamps and remove bolts).

Removal
1) Locate TPS: It’s mounted on the throttle body. On older models it’s a small rectangular sensor with a connector. On integrated modern throttle bodies the sensor is built into the housing and may require removing the entire throttle body assembly.

2) Unplug electrical connector: Depress tab and pull straight out. If corroded, spray a tiny amount of electrical contact cleaner and gently clean pins.

3) Mark orientation (optional): If the sensor has a keyed position, note orientation or mark it with a small paint dot to ensure correct alignment on reassembly. Many TPS units are indexed and must be fitted exactly.

4) Remove mounting screws/bolts: Use the appropriate socket or Torx. Keep hardware organized.

5) Remove sensor (or throttle body): Gently pull it off the throttle shaft. Some sensors have a small O‑ring; inspect it and replace if torn.

6) Compare old and new parts: Check pin count, shape, and shaft alignment. New sensor should match old exactly.

Installation
1) Install new TPS onto shaft in the same orientation. Do not force — ensure the taper/slot keys engage. If replacing the whole throttle body, fit new gasket and torque bolts to spec.

2) Torque bolts to manufacturer spec (if you have it). If not available, snug and add small fraction — typically 4–8 Nm for small sensor bolts. Avoid over‑torquing plastic bosses.

3) Reconnect connector. Apply a tiny smear of dielectric grease to pins if desired to reduce future corrosion.

4) Reinstall intake duct/airbox and any removed components.

5) Reconnect negative battery terminal if disconnected.

ECM relearn / calibration
- Some Mazda3 models require a throttle position or throttle body relearn after replacement. Methods vary:
- Preferred: Use a dealer-level or aftermarket scan tool to run “Throttle Body Alignment” or “Throttle Relearn” procedure.
- If no scanner: Many ECMs automatically relearn. Typical manual procedure (general, safe approach):
1) With everything reconnected, turn ignition to ON (do not start) for ~5 seconds, then OFF for 5 seconds. Repeat 3 times.
2) Start engine and let it idle without touching throttle until it reaches normal operating temperature and idle stabilizes (may take several minutes).
3) With the engine warmed, perform a few gentle full-throttle blips up to ~3000 rpm, then let it return to idle and remain for a minute.
4) Drive gently for several miles allowing the computer to adjust.
- If you see persistent codes or limp behavior, you need a scan tool to perform relearn.

Post‑repair testing (verify success)
- Clear codes with scanner, if possible.
- Start engine, watch live TPS voltage — it should be smooth and in expected range (0.4–1.0 V closed, rising to ~4.0+ at WOT).
- Verify APP and TPS track each other in live data while you slowly press the accelerator.
- Test drive: check for normal idle, responsiveness, no CEL.

Common things that can go wrong (pitfalls)
- Replacing only sensor when the wiring or ECM is the issue — always check wiring & reference voltage first.
- Misalignment: installing sensor slightly off results in incorrect readings.
- Over‑torquing bolts and cracking throttle body plastic or sensor housing.
- Contaminating the sensor with harsh cleaner or getting debris into the throttle body.
- Forgetting relearn/calibration — results may be limp mode or rough idle.
- Replacing sensor when throttle body is integrated: buying the sensor as a separate part when it’s non‑serviceable wastes time & money.
- Loose or corroded connector causing intermittent faults.
- Ignoring related sensors: MAF, MAP, vacuum leaks or APP sensor faults can mimic TPS problems.

Troubleshooting tips
- If TPS voltage is zero or stuck at a voltage that doesn’t change, but 5V reference exists, wiring to signal is open or sensor failed.
- If 5V reference is missing, check fuse, ECM, or wiring upstream — do not assume the TPS is bad.
- Intermittent problems: wiggle test wiring while watching live data to reproduce faults.
- If you cleaned the throttle body and idle worsened, it may need a relearn or cleaning removed protective oily film used in some sensors — let it sit or perform relearn.

When to replace the whole throttle body
- If your Mazda3’s TPS is integrated, or if the throttle motor or shaft seals are damaged, replace the entire throttle body assembly (more expensive, but necessary).
- If there is physical damage to the throttle body or heavy carbon that cannot be cleaned safely.

Parts and costs (ballpark)
- Replacement TPS (separate) varies by year: –0.
- Throttle body assembly (integrated) typically 0–0 depending on year/part and OEM vs aftermarket.
- Labor DIY: 0.5–2 hours depending on whether replacing sensor only or entire throttle body.

Final checklist before finishing
- Confirm connector fully seated and locked.
- Replace any damaged seals/gaskets.
- Clear codes and verify no new codes appear after test drive.
- Confirm throttle response and idle are normal.

Quick troubleshooting table (short)
- CEL + P0120–P0122 + erratic voltage → suspect TPS sensor or wiring.
- No 5V at reference pin → wiring/fuse/ECM issue.
- Smooth voltage but poor driveability still → check MAF/MAP, vacuum leaks, fuel system.
- Replaced TPS but CEL returns immediately → check wiring harness/ECM and correct part fitment.

That’s the full picture — theory, components, diagnosis, step‑by‑step replacement, relearn, tests and common failures. Follow model‑specific service manual torque and wiring diagrams when available. Good luck.
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