1989 Eagle Summit ECM: Diagnosing Stalling and No-Start from Capacitor Failure
This guide covers the common failure points, symptoms, and replacement realities for the Engine Control Module in the 1989 Eagle Summit 1.6L DOHC.
- The primary cause of failure for this ECM is leaking internal capacitors, a common issue for Mitsubishi electronics of this era.
- Symptoms include stalling, no-start, erratic idle, and a distinct 'rotten fish' smell from the passenger footwell.
- This ECM is plug-and-play and does NOT require any programming or flashing for installation.
- When buying a used ECM, it is critical to match the part number (MD131841) and have the capacitors professionally replaced before installation to ensure reliability.
The #1 Problem: Leaking Capacitors
If you have a 1989 Eagle Summit, which is based on a Mitsubishi platform, its original ECM is a ticking time bomb. The most common and well-documented issue for these modules is failure of the internal electrolytic capacitors. Over time, due to age and heat cycles, these electronic components leak an acidic fluid onto the circuit board. This fluid is corrosive and can eat away at the delicate copper pathways (traces) on the board, leading to short circuits and a host of bizarre, intermittent problems.
Warning: A distinctive, faint smell of rotten fish or seafood inside the car, often near the passenger footwell, is a classic sign of a leaking ECU. If you smell this, the capacitors are actively leaking and damaging the board. Action should be taken immediately to prevent permanent, unrepairable damage to the module.
Symptoms of a Failing 1989 Summit ECM
ECM failure, especially from leaking capacitors, can cause a wide range of confusing symptoms that may come and go.
- Engine Stalling or No-Start: The engine may crank but refuse to start, or it may stall randomly while driving or at idle.
- Erratic Idle: The engine may hunt for idle, surging up and down, or idle very roughly.
- Rapid Clicking Under Dash: A fast clicking or chattering sound from the passenger side dash area can occur. This is the ECM getting stuck in a constant reboot cycle due to unstable power from the failing capacitors.
- Check Engine Light: The light may be on constantly, or it may flicker randomly. You may find nonsensical trouble codes stored in the system, or you may be unable to communicate with the computer at all.
- Poor Engine Performance: This can include hesitation, loss of power, engine misfires, and a sudden drop in fuel economy.
- Rich Fuel Smell: The ECM may fail to properly control the fuel injectors, causing the engine to run excessively rich.
Diagnosing the Problem
Step 1: Physical Inspection
The ECM is located behind the passenger side (RH) kick panel. To access it, you will need to remove the plastic panel in the passenger footwell next to the door. Once you unbolt and unplug the metal-cased ECM, open it by removing the screws holding the top and bottom covers. Look and smell for:
- Leaking Capacitors: Check the three or four barrel-shaped capacitors on the board. Look for any bulging tops, crusty residue at their base, or wet-looking spots on the board around them.
- Fishy Smell: A strong smell of rotten seafood from the open case confirms leaking capacitors.
- Board Damage: Look for any dark, discolored, or corroded areas on the circuit board, especially near the capacitors.
Step 2: Reading Trouble Codes (OBD-I)
Your 1989 Summit uses an early diagnostic system called OBD-I. You do not need a modern scanner to read these codes.
- Locate the diagnostic connector in the fuse box.
- Ground a test light and insert the probe into terminal #1 of the connector.
- Turn the ignition key to the 'ON' position (do not start the engine).
- The 'CHECK ENGINE' light will begin to flash. Count the flashes. Long flashes are the 'tens' digit, and short flashes are the 'ones' digit. For example, two long flashes followed by three short flashes is Code 23.
- Once repairs are made, you can clear the codes by disconnecting the negative battery terminal for at least 30 seconds.
Common codes associated with ECM-related systems include:
| Code | Meaning |
|---|---|
| 11 | Oxygen Sensor |
| 12 | Airflow Sensor |
| 14 | Throttle Position Sensor |
| 22 | Crank Angle Sensor |
| 23 | Top Dead Center Sensor |
| 41 | Injector |
| 44 | Ignition Coil / Power Transistor |
| 61 | ECM to Transaxle Interlink Fault |
| 63 | EPROM Write Denied (Faulty ECM) |
While codes for sensors can indicate a bad sensor, they can also be triggered by a faulty ECM that can no longer properly read the sensor's signal. A Code 63 directly points to an internal ECM failure.
Buying a Used Engine Control Module (ECM)
Since new and remanufactured ECMs for this vehicle are generally no longer available, buying a used part is often the only option. However, you must be extremely careful.
Pro Tip: Assume that ANY used or original 1989 Summit ECM either has leaking capacitors or will leak soon. The best practice is to either buy a unit that has been professionally rebuilt and 'recapped' (had its capacitors replaced) or to send your purchased used ECM to a repair service for capacitor replacement before you install it in your vehicle. Installing a used unit without servicing it is asking for the same problems to return.
- Match Part Numbers Exactly: You must match the OEM part number on the case of your original ECM. The primary part number for the 1.6L DOHC model is MD131841. Do not install a module with a different part number, even if it looks identical.
- Physical Inspection: When buying in person, open the case. Do not buy a unit that shows any signs of dark, burnt spots, previous leaky capacitor residue, or corrosion.
- Check for Botched Repairs: Look for sloppy solder work or damaged traces on the board, which indicate a previous, failed repair attempt.
Installation and Programming
Does this module need to be programmed?
No. The ECM for a 1989 Eagle Summit is plug-and-play. It does not need to be programmed, flashed, or coded to your vehicle's VIN. There is no anti-theft system linked to the ECM on this model year. Installation is purely a mechanical process.
Replacement Procedure
- Disconnect the negative battery terminal.
- Remove the passenger side kick panel to expose the ECM.
- Unplug the wiring harness connectors from the ECM. They have locking tabs that must be depressed.
- Unbolt the ECM from its mounting bracket.
- Install the new (or repaired) ECM, reconnect the harnesses, and re-mount it.
- Re-install the kick panel and reconnect the battery.
Cost to Replace a 1989 Summit ECM
The cost can vary widely depending on the solution you choose.
| Option | Estimated Cost | Notes |
|---|---|---|
| New OEM | N/A | Discontinued and no longer available from Chrysler/Mitsubishi. |
| New Aftermarket | N/A | Not manufactured for this vehicle. |
| Remanufactured | $250 - $450+ | Extremely rare and not commonly available from major suppliers. Availability is very low. |
| Used OEM | $50 - $150 | Widely available on sites like eBay, but will require capacitor service. |
| Repair Service | $100 - $300 | You send your original or a used unit to a specialist for capacitor replacement and board cleaning. |
| Shop Labor | $75 - $150 | Typically less than an hour of labor for diagnosis and replacement. |
Recalls and Technical Service Bulletins (TSBs)
As of this writing, there are no active safety recalls or technical service bulletins issued by the NHTSA for the Engine Control Module on the 1989 Eagle Summit.
Frequently Asked Questions (FAQ)
Does the 1989 Eagle Summit ECM need to be programmed?
No. This is a pre-OBD-II module and it is completely plug-and-play. It does not require any programming, flashing, or key matching.
What is the main reason these ECMs fail?
The primary cause of failure is leaking electrolytic capacitors inside the unit. This is a very common problem for Japanese electronics from the late 1980s and early 1990s.
My mechanic says my car has a bad oxygen sensor and crank sensor. Could it still be the ECM?
Yes. A failing ECM can no longer correctly interpret the signals from its sensors, causing it to generate false trouble codes for perfectly good parts. If multiple, seemingly unrelated sensor codes appear at once, the ECM itself is a likely suspect.
Can I use an ECM from a 1.5L Summit or a later model year?
No. You must use an ECM with the exact same part number as your original. The fuel and timing maps are specific to the 1.6L DOHC engine. Using the wrong module will result in poor performance or a no-start condition.
Is it safe to repair my own ECM by replacing the capacitors?
If you are experienced with soldering and electronics repair, it is possible. You must be careful not to damage the circuit board and to clean any leaked electrolyte thoroughly. For most people, sending the unit to a professional repair service is a safer and more reliable option.
Technical Specifications
OEM Part Numbers: MD131841 MD131842
Located behind the passenger side (RH) kick panel. Fits 1.6L DOHC Federal and Canada emission models.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Eagle Summit:
- 🛍️ Shop This Part
- The #1 Problem: Leaking Capacitors
- Symptoms of a Failing 1989 Summit ECM
- Diagnosing the Problem
- Step 1: Physical Inspection
- Step 2: Reading Trouble Codes (OBD-I)
- Buying a Used Engine Control Module (ECM)
- Installation and Programming
- Does this module need to be programmed?
- Replacement Procedure
- Cost to Replace a 1989 Summit ECM
- Recalls and Technical Service Bulletins (TSBs)
- Frequently Asked Questions (FAQ)
- 🎟️ Get 5% Off