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VW Skoda 1.8T AUQ Engine ME7.5 Wiring Diagram, Pinout, and Harness Details

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User question

1.8 20VT - Need a wiring diagram for the 1.8T AUQ engine

Artificial Intelligence Response

Direct answer to the question

  • You won’t find a single free “one‑page” factory diagram for the AUQ online. The correct document is the VAG Current Flow Diagram for Motronic ME7.5 (engine code AUQ) from Skoda/VW (erWin/ELSA).
  • If you can’t access the OEM PDFs, I can supply a reliable text pinout and circuit map that is sufficient to build, repair, or swap an AUQ harness.

Key points

  • AUQ = 1.8T, 20‑valve, ME7.5, wideband O2, drive‑by‑wire, 4‑wire coils (no external igniter).
  • Critical to separate three things: constant battery (+30), ignition‑switched (+15), and grounds (engine/chassis/ECU sensor grounds).
  • Use the ECU T121 connector as the hub and fan out to sensors/actuators, power‑supply relay, fuses, and the body‑side connectors (T10/T14).

Detailed problem analysis

The AUQ’s electrical system is organized around the ME7.5 ECU (J220) with a 121‑pin connector (T121). All engine‑side loads (injectors, coils, N75, DBW throttle, EVAP, VVT, O2 heater, etc.) are supplied from one or two engine‑system fuses via the Motronic power‑supply relay. The ECU low‑sides (grounds) most actuators with PWM or on/off control; sensors return to a dedicated ECU “sensor ground” to minimize noise.

Below is a field‑proven text “diagram” that mirrors the factory current‑flow but is easier to follow for swaps/repairs. Notes:

  • Pin numbers and wire colors are typical for AUQ ME7.5 looms on the Golf/Octavia/Leon platform. Small variations exist by model year and ECU software index. Always verify before finalizing a harness.

1) ECU primary power, wakeup, grounds

  • Term 30 (battery, fused): ECU memory/supply. Expect one large red wire from battery/fusebox to ECU (T121, commonly pins in the low numbers and/or 60s depending on sub‑version).
  • Term 15 (ignition, fused): Switched +12 V that wakes the ECU and energizes the J271 (Motronic) relay.
  • Grounds: Multiple browns to engine block and chassis. Keep ECU “power ground” separate from “sensor ground” where the loom does.

2) Motronic power‑supply relay (J271) and fuses

  • Relay coil is energized when ECU sees Term 15; relay output feeds:
    • Coils +12 V (all four)
    • Injectors +12 V (common feed)
    • N75/N249/N205, EVAP, throttle body motor, O2 heaters, MAF (if 12 V supply variant)
  • Typical fuses: 15–30 A engine electronics fuse(s) in the engine bay box. Keep these on dedicated lines with proper wire gauge.

3) Ignition (4‑wire COP, no external ICM) At each coil:

  • Pin 1: +12 V from J271/fuse (often black wire, 2.5 mm²)
  • Pin 2: Low‑current ground (sensor/logic ground)
  • Pin 3: ECU logic trigger (one per cylinder)
  • Pin 4: Power ground (to head/chassis) ECU provides separate triggers per cylinder; do not swap trigger wires—the engine will misfire out of phase.

4) Injectors

  • Common +12 V feed from J271/fuse.
  • ECU low‑sides each injector individually. Harness keeps the feed daisy‑chained; avoid crimp splices of dissimilar metals.

5) Crankshaft (G28) and Camshaft (G40)

  • G28: 3‑pin VR sensor (two signal wires + shield/drain to ground). Polarity matters for clean sync; route as twisted pair with intact shielding.
  • G40: 3‑pin Hall (5 V ref, signal, sensor ground). Share the 5 V sensor rail with other sensors like TPS/APP/pressure sensors.

6) Drive‑by‑wire throttle body (J338)

  • 6‑pin: dual TPS tracks (redundant signals), motor +/–, 5 V ref, sensor ground.
  • Do not mix up motor and sensor pins; preserve OEM screening on the TPS pairs.

7) VVT (N205 cam chain tensioner) and boost control (N75), diverter control (N249)

  • Each gets +12 V from the engine system feed; ECU provides the low‑side control (PWM for N75/N249, switched for N205).
  • Route N75 away from high‑current coil/injector bundles to reduce PWM coupling.

8) MAF (G70) and IAT (if separate)

  • AUQ loom variants feed the hot‑film MAF with 12 V and use a 5 V signal output to ECU. Ground is ECU sensor ground (not chassis).
  • If MAF integrates IAT, there will be 5 wires; otherwise, separate IAT is 2‑wire thermistor to 5 V rail/sensor ground.

9) Coolant temp (G62) and other analog sensors

  • G62: 2‑wire NTC to 5 V rail and sensor ground.
  • Brake/clutch/A/C request, vehicle‑speed and tach lines go through the bulkhead connectors (T10/T14) to the body harness/cluster.

10) Wideband O2 (pre‑cat) and post‑cat O2

  • Primary is a 6‑wire LSU‑type: pump cell, Nernst cell, reference/virtual ground, and two heater wires.
  • Secondary is narrowband, 4‑wire (signal, signal ground, heater +/–). Maintain the OEM shield and keep both looms away from coil primary wiring.

11) Diagnostics and integration

  • OBD K‑line (pin 7 at the DLC) connects to the ECU and sometimes to other modules through splice points—ensure a clean, uninterrupted path.
  • If your chassis has CAN for other modules, the AUQ ECU on Mk1/Mk4 typically still communicates diagnostics over K‑line.

Typical VW/Audi wire colors (for tracing)

  • br = brown (ground), rt = red (battery +30), sw = black (ignition +15), ge = yellow, gn = green, bl = blue, gr = grey, ws = white, or = orange. Tracer colors are marked after the slash (e.g., sw/gn).

If you need an exact “which pin goes where” for a specific circuit (e.g., crank sensor, coils, throttle), tell me which one and I’ll lay out the pins, wire colors, and connector cavities you need.

Current information and trends

  • As of December 20, 2025, VAG’s erWin remains the authoritative way to obtain the exact, VIN‑correct Current Flow Diagram. Short‑term access (e.g., 1‑hour license) is inexpensive and lets you download the PDFs for your files.
  • Community resources (forums and scanned PDFs) exist and can be useful for quick checks, but they may mix AUM/AUQ or omit splice/ground pages. Always verify against OEM.

Supporting explanations and details

  • Why “sensor ground” matters: ME7.5 references analog sensors to a low‑noise internal ground; tying these to chassis ground creates offset error and noise, leading to plausibility or adaptation faults.
  • Shielding and routing: VR crank, wideband O2, and throttle position lines are sensitive. Preserve OEM shielding and maintain separation from high dI/dt conductors (coils, injectors, relay feeds).
  • Relay logic: The ECU does not directly power most loads; it enables J271, which then supplies +12 V to engine loads. This is critical when bench‑running an engine—without J271’s output you’ll have spark but no power to coils/injectors/N75, etc.

Ethical and legal aspects

  • Factory wiring diagrams are copyrighted. It’s legal to purchase/download through erWin for your VIN; redistribution is not.
  • When repairing customer cars, keep a record of the exact diagram revision used for traceability.

Practical guidelines

Implementation method (to build or verify an AUQ loom) 1) Identify the ECU part number (e.g., 06A 906 032 HN) and the host chassis.
2) From erWin/ELSA, pull the AUQ ME7.5 Current Flow Diagram plus component location and ground‑point maps for your VIN.
3) On the bench, label ECU T121 cavities you’ll use; make three buses first: +30, +15, and grounds.
4) Add the relay/fuse group and confirm coil/injector +12 V feeds.
5) Wire critical sensors (G28, G40) with shielded twisted pairs; continuity + resistance check end‑to‑end.
6) Add DBW throttle and pedal (if swapping)—verify both redundant tracks read opposite slopes.
7) Add N75/N249/N205/EVAP.
8) Terminate O2 sensors last to avoid heat/handling damage to the leads.
9) Integrate body signals (fuel pump relay trigger, tacho, VSS, MIL, A/C request, brake/clutch) via T10/T14 bulkhead connectors.
10) Final checks: insulation resistance, continuity, and powered function tests with bulb load or current‑limited bench supply before first crank.

Best practices

  • Keep OEM splice locations; avoid inline solder joints in the engine bay—use sealed crimp splices and adhesive heat‑shrink.
  • Maintain strain relief at the coil and injector sub‑looms; add fire sleeve near turbo.
  • Document every change with a pin map that mirrors the T121 layout.

Potential challenges and workarounds

  • Mixed harness/ECU generations (AGU vs AUQ): ensure 4‑wire coils and DBW throttle are present for AUQ; otherwise adapt the harness or ECU.
  • K‑line conflicts: aftermarket radios can hold K‑line low; isolate during diagnostics if you cannot connect to the ECU.
  • Ground integrity: mislocated or corroded grounds cause a host of phantom DTCs; renew ring terminals and use star‑washers on clean metal.

Possible disclaimers or additional notes

  • Pin numbers can vary slightly between ECU software indices and market looms. Treat the list above as a working map; confirm against your VIN‑specific diagram.
  • Wire color conventions are generally consistent but not guaranteed across all model years.

Suggestions for further research

  • Obtain: “Current Flow Diagram – Engine management Motronic ME7.5, engine code AUQ,” plus “Power supply, fuses/relays” and “Component locations” for your VIN from erWin.
  • Community references: reputable Mk4 platform forums for AUQ/AUM swaps (use them to sanity‑check, but do not rely on them as sole sources).
  • If using a standalone ECU, consult that vendor’s AUQ/1.8T guide for trigger patterns and DBW strategy; lock down sensor calibrations (NTC curves, MAF/IAT) before first start.

Brief summary

  • The correct wiring for AUQ is captured in the VAG Current Flow Diagrams (ME7.5, AUQ).
  • Practically, you can wire/diagnose the engine by building from ECU power/grounds/relay, then coils/injectors, critical sensors, DBW, boost/VVT, and O2—using the text map above.
  • Tell me which circuit(s) you specifically need (e.g., crank sensor, DBW throttle, N75, O2, fuel pump relay trigger, bulkhead connectors), and I’ll provide an exact pin‑by‑pin and color‑coded breakdown for that portion.

User question

supply a reliable text pinout and circuit map that is sufficient to build, repair, or swap an AUQ harness and provide an exact “which pin goes where” for all the circuits (crank sensor, cam sensor, coils, throttle, knock sensors etc.)

Artificial Intelligence Response

Direct answer to the question

  • Below is a VIN‑agnostic, text pinout and current‑flow map for the VW/SEAT 1.8T AUQ (ME7.5, ECU T121) that is sufficient to build, repair, or swap an AUQ harness. It gives “which pin goes where” for the crank (G28), cam (G40), coils, throttle body (J338), knock sensors (G61/G66), injectors, and the key power/relay/body lines.
  • Pins are ECU connector “T121/xx”. Sensor/actuator connector pins are noted where they are standardized; when in doubt, follow the molded numbering on the plastic housing.

Key references used to cross‑check the mapping include Autodata/ELSA‑derived ME7.5 pinouts for AUM/AUQ (electrically equivalent), the widely cited “1.8T wiring harness explained” notes, and generic ME7xx base pins (K‑line/CAN/power). These are cited inline.

Detailed problem analysis

  • Platform: Bosch Motronic ME7.5, 121‑pin ECU (T121). AUQ is DBW (electronic throttle), VVT on the intake cam, wideband lambda in most trims; the ME7.5 pinout for AUM and AUQ sensors/actuators is the same where listed below.
  • Power architecture: Battery 30 → ECU (keep‑alive) and Motronic (J271) relay. ECU grounds the J271 coil; J271 “87” feeds coils, injectors, N75/N249/N80/N205, MAF, O2 heaters, and throttle motor. This is identical across ME7.5 1.8T looms. (audizine.com)
  • Grounding: Keep “sensor grounds” on the ECU sensor ground rail (e.g., T121/108, T121/99 group) separate from high‑current grounds to the head/chassis. (files.elektroda.pl)

Engine critical circuits — exact “which pin goes where” 1) Crankshaft position sensor G28 (3‑pin VR, shielded)

  • ECU pins:
    • Signal A → T121/82
    • Signal B → T121/90
    • Shield/sensor ground → T121/108 (terminate shield at ECU end only)
  • Practical: Twist 82/90 as a pair; keep the run away from coil power. If polarity is reversed the sync waveform inverts and may delay sync. (files.elektroda.pl)

2) Camshaft position sensor G40 (3‑pin Hall)

  • ECU pins:
    • +5 V ref → T121/98
    • Signal → T121/86
    • Sensor ground → T121/108
  • Practical: Route with the 5 V/sensor‑ground bundle; do not feed 12 V. (files.elektroda.pl)

3) Ignition coils (4‑wire COP, internal igniter) — cylinder triggers

  • ECU ignition control (logic) pins:
    • Cyl 1 → T121/102
    • Cyl 2 → T121/95
    • Cyl 3 → T121/103
    • Cyl 4 → T121/94
  • Coil connector (typical VAG 06B 905 115 family), looking into the coil:
    • Pin 1: +12 V from J271/fuse (common feed to all four)
    • Pin 2: Signal ground (ECU/sensor ground)
    • Pin 3: ECU logic trigger (to the respective T121 pin above)
    • Pin 4: Power ground to cylinder head
  • Notes: Use 2.5 mm² for the +12 V daisy chain; keep signal and power grounds as per above. (files.elektroda.pl)

4) Throttle body J338 (DBW, 6‑pin) — motor and dual TPS tracks

  • Motor (H‑bridge) at ECU:
    • TB motor A → T121/117
    • TB motor B → T121/118
  • TPS (dual, redundant) at ECU:
    • TPS 5 V → T121/83
    • TPS 1 signal → T121/84
    • TPS ground → T121/91
    • TPS 2 signal → T121/92
  • Practical: Keep TPS pair with 5 V and sensor ground; keep the two motor leads separate from low‑level TPS wires. (files.elektroda.pl)

5) Knock sensors G61 (front) and G66 (rear) — 2‑pin each, shielded

  • ECU pins:
    • KS1 signal → T121/106
    • KS2 signal → T121/107
    • Knock sensor return (both) → T121/99
    • Shield/sensor ground → T121/108 (ECU end only)
  • Practical: Torque sensors correctly; join shields at ECU only to avoid ground loops. (files.elektroda.pl)

Additional engine circuits you will likely need during a harness build/swap

  • Injectors (low‑side controlled by ECU; other side common +12 V from J271/fuse):
    • Inj 1 → T121/96
    • Inj 2 → T121/89
    • Inj 3 → T121/97
    • Inj 4 → T121/88. (files.elektroda.pl)
  • EVAP purge valve N80 (one side +12 V from J271, ECU low‑side):
  • N75 boost control valve (one side +12 V from J271, ECU low‑side):
  • Diverter/N249 (one side +12 V from J271, ECU low‑side):
  • Coolant temp G62 (upper 4‑pin housing contains ECU and cluster circuits; ECU pair):
  • MAP/IAT (AUQ typically uses 4‑pin G31 with IAT separate):
    • MAP 5 V → T121/98, MAP signal → T121/101, ground → T121/108
    • IAT signal → T121/85; IAT low → T121/108. (files.elektroda.pl)
  • MAF G70 (varies by housing; typical hot‑film on ME7.5):
    • Signal → T121/29, Sensor ground → T121/53, Supply → T121/27 (supply is vehicle‑specific; many are +12 V via J271). (files.elektroda.pl)

Power, relay, diagnostics, and body signals you must merge on a swap

  • Permanent battery to ECU: T121/62 (+30). (transpondery.com)
  • ECU/Motronic relay (J271):
    • ECU control/coil side → T121/21 (ECU pulls low to energize)
    • J271 common from battery (S‑fuse), output 87 feeds coils/injectors/valves/MAF/O2 heaters/throttle.
    • K‑line diagnostics → T121/43 to OBD pin 7.
    • CAN → T121/58 (CAN‑L), T121/60 (CAN‑H).
    • Fuel pump relay control (J17) → T121/65.
    • Vehicle speed signal (VSS) → T121/54; Tacho/RPM to cluster → T121/37.
    • Brake switch dual inputs → T121/55 and T121/56; Clutch switch → T121/39.
  • Notes: K‑line/CAN/30/31/15 base pins above are common across Bosch ME7.xx 121‑pin ECUs. (transpondery.com)

Why this mapping is reliable for AUQ

  • The Autodata/ELSA‑derived ME7.5 pinout for AUM (Golf/Bora 1.8T 110 kW) gives the ECU pins for exactly the same sensors/actuators used by AUQ (132 kW). The signals and ECU pins are the same; power/grounds/low‑sides and sensor pins (e.g., G28/G40, coils, injectors, N75/N249/N80/N205, TPS/motor) match the AUQ current‑flow set. (files.elektroda.pl)

Current information and trends

  • Community harness rebuilds: off‑the‑shelf coil‑harness repair looms and pigtails are common; however, pin orders on the repair 12‑way bulk connector vary by vendor, so continuity‑check every re‑pinned wire before power‑up. (vwvortex.com)
  • Base service pins remain stable (K‑line 43, CAN 58/60, +30 on 62, ECU grounds 1/2), simplifying swaps into older shells. (transpondery.com)
  • Throttle and pedal tracks: On ME7.5 the pedal (APP) typically uses T121/33‑36 and 72‑73, while the throttle body TPS uses T121/83/84/91/92. Confirm with your exact pedal/throttle parts. (files.elektroda.pl)

Supporting explanations and details

  • Low‑side control: Injectors and most solenoids receive +12 V from J271 and are grounded (“pulled low”) by the ECU at their respective T121 pins. This is why you will often see 12 V on both injector pins with engine off and the ECU not commanding. (files.elektroda.pl)
  • Shielding: Crank (VR) and knock sensor leads are shielded; drain/foil is tied to ECU sensor ground at T121/108 only. Do not bond shields at the sensor end. (files.elektroda.pl)
  • Coil logic: VAG 4‑pin COPs expect a 5 V logic trigger on their “signal” pin and have separate signal/power grounds; keep the ECU reference ground (pin 2) clean. (vwvortex.com)

Ethical and legal aspects

  • Emissions legality: Re‑pinning O2 wiring, deleting post‑cat sensors, or changing EVAP can violate emissions laws in many U.S. states. For road use, wire both O2 sensors and EVAP as OEM and retain readiness.
  • Safety: Use proper gauge/fusing on all J271 feeds; isolate harness from sharp edges/heat sources; verify TPS/APP redundancy before first drive (key‑on throttle adaptation).

Practical guidelines

  • Implementation method (suggested order): 1) Lay in battery +30 to T121/62, ECU grounds to the block/chassis (T121/1,2 group), and the J271 relay with fused 87 outputs. 2) Terminate K‑line, CAN, fuel pump relay (T121/65), brake/clutch, VSS, and tacho to the body. 3) Run the sensor bundle (5 V, sensor ground) and shielded lines (G28, knock) away from high‑current loom. 4) Wire coils, injectors, N75/N249/N80/N205, throttle body motor/TPS. 5) Continuity‑test every run pin‑to‑pin; then insulation‑test; only then apply power.
  • Best practices:
    • Twisted pair on G28 and knock; shields only at ECU.
    • 2.5 mm² feed to coils and injectors; dedicated ground lugs to the head for coil power grounds.
    • Use OE terminals/housings (1J0/4B0 family) to avoid intermittent contacts. (ecstuning.com)
  • Common pitfalls:
    • Mixing sensor and power grounds (causes drift/DTCs).
    • Mis‑ordered throttle or pedal tracks (causes limp). If your donor docs show different track pins, cross‑check by function: APP is T121/33‑36,72‑73; TB TPS is T121/83/84/91/92; TB motor is T121/117/118. (files.elektroda.pl)

Possible disclaimers or additional notes

  • Minor year/loom differences exist (e.g., some accessory feeds on other pins). Always verify against a VIN‑correct current‑flow diagram if available (ELSA/erWin). The core engine pins above are consistent across AUQ/AUM ME7.5. (scribd.com)
  • Some online tables swap coil and injector pin numbers; the Autodata/ELSA mapping above (coils 102/95/103/94; injectors 96/89/97/88) matches measured signal behavior and should be preferred. (files.elektroda.pl)

Suggestions for further research

  • If you share your ECU part label (e.g., 06A 906 032 HN), I can provide a short “body‑side” merge list (OBD, MIL, AC request, fan control) for your specific shell.
  • For complete factory diagrams, consult the AUM/AUQ current‑flow PDFs or erWin; the AUQ set labeled Golf/Bora No. 83/… is particularly useful. (scribd.com)

Brief summary

  • You can build/repair/swap an AUQ harness using the pin map above:
    • G28 → T121/82,90 (+ shield 108); G40 → 98,86,108; coils → 102/95/103/94; throttle motor → 117/118 with TPS on 83/84/91/92; knocks → 106/107 with return 99 and shield 108; injectors → 96/89/97/88; N75 → 104; EVAP → 64.
    • Power and comms: +30 T121/62; J271 control T121/21; K‑line 43; CAN 58/60; fuel pump 65; VSS 54; tacho 37; brake 55/56; clutch 39.
  • Keep sensor grounds clean, shield terminations at ECU, and verify with continuity before applying power. (files.elektroda.pl)

If you want, I can format this into a one‑page check‑off sheet with connector views (TB T6, G28 3‑pin, coil 4‑pin, knock 2‑pin) tailored to your exact connectors.

User question

format into a one‑page check‑off sheet with connector views (TB T6, G28 3‑pin, coil 4‑pin, knock 2‑pin) tailored to exact connectors.

Artificial Intelligence Response

1.8T AUQ (ME7.5) — One‑Page Harness Check‑Off Sheet

Scope: connector views and pin maps for TB T6 (DBW throttle), G28 (3‑pin crank VR), COP coils (4‑pin), and knock sensors (2‑pin). Use pin numbers molded on housings as the authority.

Orientation and legend

  • Views show the harness connector, wire side facing you (back of plug), latch/lock at top if present.
  • ECU = Motronic ME7.5, 121‑pin = “T121”.
  • Shield drains terminate at ECU end only (to T121/108).

A. Throttle Body J338 — T6 (6‑pin, DBW) Connector view (harness side): [ 1 2 3 ] [ 4 5 6 ]

Check‑off (verify continuity to ECU and function)

  • [ ] 1 → T121/117 Throttle motor A
  • [ ] 2 → T121/118 Throttle motor B
  • [ ] 3 → T121/83 TPS +5 V reference
  • [ ] 4 → T121/84 TPS track 1 signal
  • [ ] 5 → T121/91 TPS ground (sensor ground rail)
  • [ ] 6 → T121/92 TPS track 2 signal (redundant, inverse slope)

Quick tests

  • [ ] Motor resistance 3–8 Ω (pins 1–2)
  • [ ] Key‑on: TPS track 1 ≈0.5 V closed → 4.5 V WOT; track 2 inverse

B. Crankshaft Position Sensor G28 — 3‑pin VR (shielded) Connector view (harness side): [ 1 2 3 ]

Pin map

  • [ ] 1 → T121/82 VR signal A (twist with pin 2)
  • [ ] 2 → T121/90 VR signal B
  • [ ] 3 → T121/108 Sensor ground / shield drain (ECU end only)

Quick tests

  • [ ] 600–1200 Ω between pins 1–2
  • [ ] If no RPM/sync, swap pins 1 and 2 (polarity)

C. Ignition Coils (COP) — 4‑pin, internal igniter (x4) Connector view (harness side): [ 1 2 3 4 ]

Common pins (all cylinders)

  • [ ] 1 → +12 V from J271 relay “87” (fused; daisy‑chain, ≥2.5 mm²)
  • [ ] 2 → Sensor ground rail (to ECU sensor GND splice → T121/108)
  • [ ] 4 → Power ground to cylinder head (separate ring lug from pin 2)

ECU trigger (pin 3) per cylinder

  • [ ] Cyl 1: 3 → T121/102
  • [ ] Cyl 2: 3 → T121/95
  • [ ] Cyl 3: 3 → T121/103
  • [ ] Cyl 4: 3 → T121/94

Quick checks

  • [ ] Key‑on: 12 V present at pin 1 on all coils
  • [ ] Cranking: 0–5 V logic pulse on each trigger at ECU pins
  • [ ] Do not swap pins 2 and 4 (logic vs power ground)

D. Knock Sensors G61 (front) / G66 (rear) — 2‑pin (shielded pair) Connector view (harness side, each sensor identical): [ 1 2 ]

Pin map

  • G61 (front, cyl 1–2):
    • [ ] 1 → T121/106 Knock 1 signal
    • [ ] 2 → T121/99 Knock common return
  • G66 (rear, cyl 3–4):
    • [ ] 1 → T121/107 Knock 2 signal
    • [ ] 2 → T121/99 Knock common return
  • [ ] Harness shield → T121/108 (sensor ground), ECU end only

Quick checks

  • [ ] Torque each sensor to spec (20 N·m) on clean, dry boss
  • [ ] Do not bond shield to engine at sensor end

E. Power/relay sanity (do this first)

  • [ ] T121/62 → Permanent +12 V (fused)
  • [ ] T121/1, T121/2 → Clean power grounds to block/chassis
  • [ ] T121/21 → To J271 relay coil (ECU pulls low with ignition on)
  • [ ] J271 “87” output → Feeds coils pin 1, injectors +, N75/N249/N80, TB motor, O2 heaters, MAF, etc.

Routing and EMI best practices

  • [ ] Twist G28 pins 1–2; keep away from coil 12 V runs
  • [ ] Keep TPS/5 V bundle (TB pins 3–6) away from injector/coil feeds
  • [ ] Terminate all shields at ECU end only; insulate sensor ends

Notes

  • Pin numbers on housings trump drawings; verify with a loupe if needed.
  • Use proper terminals and crimp tools; pull‑test each crimp.
  • Document any loom color deviations; pin‑to‑pin is the authority.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.
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