Changan Eado EV Remote Information Monitor (RMU) Diagnostics and Removal/Installation Guide

Fault Background

The Remote Information Monitor (RMU) of the Changan Eado EV is a multifunctional vehicle information monitoring device that supports 2G network: it monitors vehicle speed, mileage, and vehicle CAN bus data, and has remote programming and diagnostic functions; it collects GPS and vehicle CAN data and sends it to the remote information monitoring platform via a dual-mode antenna; a removable SD/TF card stores monitoring data, which can be converted to ASC/Excel format using data conversion software for analysis of vehicle operating status and fault causes. The device is located under the front passenger seat, and the antenna receiver is magnetically attached to the right A-pillar. Diagnosis relies entirely on the flashing patterns of three indicator LEDs (PWR/CAN/NET). Removal/installation is simple (M6 screw, 9±3N·m) but requires adherence to seven maintenance rules. This article is compiled as a service guide.

Overview and Connectors

Functions: Monitors vehicle speed, mileage, and vehicle CAN bus data and stores it; remote programming and diagnostics; GPS + vehicle CAN data acquisition, transmitted to the remote information monitoring platform via a dual-mode antenna; SD/TF card stores monitoring data (convertible to ASC/Excel format).

Low-voltage connector pins: 1 CAN High / 2 CAN Low / 6 DVI Input / 10 12V Power Input / 20 12V Power Signal Ground.

Construction: Power indicator (marked PWR on housing), CAN data indicator (CAN), wireless network indicator LED (NET), low-voltage connector, antenna cable length 1.5m; M6 screw mounting, tightening torque 9±3N·m. The antenna assembly has 3M adhesive on the bottom; peel off the protective layer to stick. Antenna connectors are mated by matching colors.

Discipline: Replacement parts must use identical part numbers; reassembly must use specified torque values to ensure proper tightness.

Indicator Light Interpretation and Fault Repair

Inspection and Adjustment

• Visual inspection: RMU surface free of damage, scratches, cracks;
• Antenna inspection: No damage or wear — replace if defective;
• Connector and harness inspection: Connector housings and terminals intact, no deformation or damage, terminal surfaces free of corrosion — replace if defective;
• Mounting nut and torque: Nut secure, retighten to specification if necessary — 9±3N·m.

On-Vehicle Maintenance (Seven Rules)

1. Never expose the RMU assembly to water;
2. Ensure low-voltage harness connectors are securely connected during replacement/maintenance;
3. To read local data from TF card: press the TF card lightly and release immediately; the card will eject automatically. Remember to reinsert it after use;
4. Do not arbitrarily modify files on the TF card;
5. Do not format the TF card using Windows formatting tools;
6. Do not arbitrarily move the antenna receiver position;
7. If the remote monitoring platform receives no data for a long time, first check whether the mobile data SIM card is in arrears.

Removal and Installation

Location: RMU assembly is under the front passenger seat; antenna receiver is on the right A-pillar — the back of the antenna receiver has strong magnetism and attaches to the right A-pillar. The antenna is secured along the low-voltage harness with clips.

Removal: ① Slide front passenger seat fully forward to expose the assembly → ② Disconnect low-voltage connector → ③ Disconnect antenna module → ④ Remove the nut securing the assembly and detach it from the body → ⑤ If necessary, remove the antenna receiver from the A-pillar. Installation is the reverse of removal.

Key Parameter Quick Reference

Safety Warnings

• This article is for technical reference only. RMU service must be performed by qualified technicians per OEM specifications. Replacement parts must use identical part numbers.
• Never expose the assembly to water; ensure connectors are securely mated.
• Do not format the TF card with Windows formatting tools, and do not arbitrarily modify files — formatting will corrupt the monitoring data format and render it unreadable by the platform.
• The antenna receiver position is calibrated; do not move it arbitrarily.

Service Insights

The most valuable part of this RMU section is the "three-LED interpretation table": each flashing pattern of the PWR/CAN/NET LEDs (1s period 500ms, 200ms period 100ms, 2s period 1s, 400ms alternating) corresponds to a specific troubleshooting action — if an LED is off, first check power/antenna/arrears; if flashing, first check card/harness/vehicle CAN; abnormal flashing means replace the assembly directly. This is typical "remote device field diagnosis": when no diagnostic scan tool is available, the indicator LEDs are the only interface. Two most practical field tips: if the platform receives no data for a long time, first check SIM card arrears (most common false fault); TF card ejects with a light press, and Windows formatting is prohibited (formatting destroys data format; ASC/Excel conversion relies on the original file structure). Removal/installation discipline is also simple: slide passenger seat forward → disconnect connector → disconnect antenna → remove M6 nut (9±3N·m) — but remember the antenna receiver is magnetically attached to the A-pillar and its position is calibrated; after service, restore it to the original position, otherwise signal quality will degrade directly. Finally, pin memory: pins 1/2 are CAN High/Low, pins 10/20 are 12V positive/negative — measure one pair for power and one pair for communication.

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【This article is for reference only】