If your vehicle’s starter cranks but the fuel pump remains silent, inspect the secondary fuse panel mounted beneath the dashboard on the driver’s side. Probe fuse F2 (15A) first–this powers the fuel pump relay. When voltage is absent, trace the red-violet wire backward to the 60-pin ECM connector, terminal 30. A 0.5V drop here confirms a corroded splice joint near the left strut tower.
Repair requires bypassing the factory crimp with a soldered splice and shrink tubing. Use a GXL 14-gauge wire rated for 90°C minimum. The ignition feed wire, color-coded yellow-black, splits into three branches–validate continuity at each branch with a digital multimeter. Replace any section shorter than 18 inches, as resistance spikes degrade fuel injection timing.
For the auxiliary control module, remove the glovebox liner to access the grey 12-pin connector. Pin 7 (light-blue stripe) carries the tach signal–test with the engine at 2,000 RPM to confirm 2.5V AC. If voltage drops below 1.8V, replace the crankshaft position sensor with OEM part #F6CZ-6C315-AA to prevent intermittent stalls.
Ground connections cluster behind the left front fender–clean each ring terminal with a wire brush and apply dielectric grease. The primary engine ground, a black-yellow wire, bolts to the transmission bellhousing. Ensure torque reaches 12 Nm to prevent voltage fluctuations causing false misfire codes.
Download the official service manual PDF for pinout tables–page 34 details the PCM-to-injector resistance specs (12-16 ohms). Deviations beyond ±1.5 ohms mandate a full harness inspection under the intake manifold runner, focusing on the dark-green injector wires prone to chafing against the EGR tube.
Electrical Schematic Guide for Vehicle Control Module Connections
Locate the central junction housing near the firewall, typically secured behind a protective cover. Pin 12 on connector C211 links to the fuel pump relay–verify continuity with a multimeter if starting issues persist, tracing back to the main fuse panel.
Examine the color-coded leads: the yellow wire with a green stripe feeds sensor input to the powertrain control module. Interruptions here often misfire codes; splice repair should match AWG 18 gauge to prevent voltage drop.
Identify the auxiliary power distribution block under the driver-side dash. Terminal 3 connects to the coil pack via a dark blue wire–confirm 0.5 ohms resistance or replace the harness segment if readings exceed spec.
Check the throttle position sensor wiring loom for chafing where it passes near the exhaust manifold. The white wire carries the signal; a break here triggers rough idling–reinforce with heat-resistant loom tape at points of abrasion.
Disassemble the kick panel to access the rear junction block. Pin 8 (red with white tracer) bridges the security module to the starter relay; corrosion here requires cleaning with electrical contact cleaner and dielectric grease reapplication.
Inspect the ground strap running from the chassis to the transmission bellhousing. A loose or corroded connection mimics battery drain symptoms–scrub contact surfaces with a wire brush and torque to 18 ft-lbs.
Trace the orange wire from the alternator to the battery fuse link. Voltage should measure 13.8-14.5V at idle; readings outside this range indicate alternator failure or a compromised charging circuit.
Replace the ignition switch pigtail if intermittent power loss occurs during key rotation. The grey connector backside often accumulates moisture–seal with silicone after ensuring pin alignment matches the factory service manual layout.
Finding the Secondary Control Module in Your Sedan
Begin by accessing the lower dashboard panel beneath the steering column on the driver’s side. Remove the three 8mm bolts securing the plastic cover–use a socket wrench with a 1/4-inch drive for precision. The module sits directly behind this panel, attached to the firewall’s inner brace with a single 10mm bolt and two snap-in clips. If obstructed, disconnect the negative battery terminal first to avoid short circuits; wait five minutes before proceeding.
The component is a rectangular metal casing, approximately 15cm by 10cm, with a wiring harness connector on its top edge. Identify it by the label stamped on the housing: “CJB” (Central Junction Block) or “ICM” (Ignition Control Module). Avoid mistaking it for the larger fuse box adjacent to it–the fuse box has a hinged lid and lacks the cylindrical relays present on the target unit.
| Feature | Secondary Control Module | Adjacent Fuse Box |
|---|---|---|
| Shape | Rectangular, compact | Larger, square with lid |
| Mounting | Single bolt + clips | Four screws |
| Label | “CJB” or “ICM” | “Fuse Panel” |
| Connectors | One multi-pin harness | Multiple fuse slots |
If corrosion is visible on the connectors, apply electrical contact cleaner to the pins and use a nylon brush for removal. Replace the harness if pins are bent–compatibility codes are stamped on the module’s side (e.g., “F5LP-14A364-AA”). For reinstallation, align the snap-in clips first before tightening the 10mm bolt to 8-10 Nm torque.
In models with manual climate controls, the module shares space with the blower motor resistor–separate them by unplugging the resistor’s two-pin connector (gray/white wires). Automatic climate versions position the module further left, requiring removal of the knee bolster for full access. Use a flashlight to inspect dark areas; dirt accumulation can obscure the module’s mounting points.
For diagnostic purposes, probe the harness connector’s pins with a multimeter: pin 12 should show 12V with the key in the “ON” position, while pin 45 grounds to the chassis. Deviations indicate upstream failures in the power distribution network or ground path. Always cross-reference readings with the vehicle’s service manual–aftermarket diagrams often omit updates from the original OEM specifications.
Alternative Locations
On rare occasions, the unit may relocate to the passenger-side footwell if aftermarket modifications were made. Check behind the glove compartment lining; the module might nestle alongside the evaporator housing. Look for modified wiring looms–cut-and-soldered connections signal previous tampering. If found here, trace the harness back to its original path for correct reinstallation.
Locating and Decoding Control Module Plug Configurations
Start by isolating the black plastic housing beneath the dashboard’s left panel–this cluster links to four primary plugs. Label them immediately: C1 (dark blue, 24-pin), C2 (tan, 12-pin), C3 (gray, 8-pin), and C4 (white, 6-pin). Use a multimeter set to continuity mode to verify each terminal’s function against the following assignments, beginning with the highest-pin connector.
- C1 pin 1: Ignition coil trigger (red/purple stripe, 12V pulse)
- C1 pin 3: Fuel pump relay control (pink/black stripe, 0.5V drop when active)
- C1 pin 5: Tachometer signal (white/blue stripe, AC voltage)
- C1 pin 7: Oxygen sensor heater (gray/yellow, 0.2V reference)
- C1 pin 9: Canister purge solenoid (dark green/white, PWM 50Hz)
- C1 pin 11: EVAP vent valve (light blue/orange, ground-switched)
For C2, focus on the tan harness: pin 2 delivers constant battery voltage (yellow/black) to the PCM, while pin 8 carries the MIL (malfunction indicator) signal (dark green/orange). Measure resistance between C2 pin 4 and chassis ground–expect 30-60 ohms for the knock sensor circuit; values outside this range indicate wire fray or corrosion at the harness’s firewall grommet. Trace the gray C3 plug to its backside; three of its pins share a common ground plane (pins 1, 4, 7), simplifying continuity checks.
- Disconnect the white C4 plug before probing: pin 3 feeds 5V reference to the throttle position sensor (TPS).
- Attach a scope to C4 pin 5–idle air control (IAC) valve should show 100-150Hz square wave.
- If C4 pin 6 reads 0V, suspect an open in the dark blue/yellow wire leading to the mass air flow (MAF) sensor.
Map each connector’s back-probing points with 22-gauge pins before reassembly to prevent terminal spread. Record voltage readings under key-on and cranking conditions for later troubleshooting–C1 pin 13 typically drops to 0.8V during ignition coil dwell, while C2 pin 10 should stabilize at 2.5V for engine coolant temperature (ECT) input at 88°C.
Step-by-Step Guide to Mapping Control Module Circuit Paths
Begin by locating the vehicle’s main fuse panel and identifying the relay labeled for spark distribution. Use a multimeter set to continuity mode to probe the terminals–pin 87 should show direct linkage to the coil pack’s positive terminal. If resistance exceeds 0.5 ohms, inspect the harness for corrosion at connectors C112 and C125, particularly where wires exit near the firewall grommet.
Isolating Signal Feeds from Sensors
Trace the crankshaft position sender wire (typically a yellow-striped lead) from the control module’s connector to its termination at the sensor. Confirm voltage fluctuations between 0.5V and 4.5V AC while cranking; static readings indicate an open circuit. For camshaft position inputs, follow the violet-striped wire to the distributor–verify Hall-effect signal pulses using an oscilloscope with a 5V/div setting.
Label each lead with masking tape as you verify its path: blue for power feeds, green for grounds, and red for sensor returns. Cross-reference findings with a pinout chart specific to the 2.5L DOHC variant–discrepancies often reveal aftermarket splices or rodent damage, especially in clusters where wires bundle near the starter solenoid.