ECU Capacitor Repair Kit for Lexus LS400 SC400 1990 1991 1992 1993 1994

Repair or help prevent age-related capacitor failure in the original Denso engine-control computer used in early 1990-1994 Lexus LS400 and SC400 models.

This complete component kit contains eleven high-quality, long-life Nippon Chemi-Con electrolytic capacitors rated for operation at temperatures up to 105°C. It is intended for experienced electronics technicians rebuilding the original 1UZ-FE engine ECU.

Product details

• Product type: Engine ECU capacitor repair kit

• Application: Denso engine control unit / ECU / ECM

• Engine: 4.0-liter 1UZ-FE V8

• Number of capacitors supplied: 11

• Capacitor manufacturer: Nippon Chemi-Con

• Temperature rating: 105°C

• Installation type: Through-hole soldered components

• Condition: New

• Repair skill level: Advanced

This is a component kit only. An ECU, repair service, installation instructions, tools, and replacement circuit-board components are not included.

Kit contents

• (11qty) High Quality Electrolytic Polar Capacitors

Supplied capacitors may have voltage ratings higher than the original components. A higher voltage rating is acceptable when the capacitance, polarity, physical dimensions, temperature rating, and lead spacing are suitable.

Compatibility

Designed for the original engine ECU in the following 1UZ-FE-powered vehicles:

• 1990 Lexus LS400, UCF10

• 1991 Lexus LS400, UCF10

• 1992 Lexus LS400, UCF10

• 1993 Lexus LS400, UCF10

• 1994 Lexus LS400, UCF10

• 1992 Lexus SC400, UZZ30

• 1993 Lexus SC400, UZZ30

• 1994 Lexus SC400, UZZ30

The Lexus SC400 was not offered for the 1990 or 1991 model year.

ECU capacitor quantities

Different ECU revisions do not necessarily use every capacitor supplied in this kit:

• 1990–1992 LS400 ECUs commonly use 10 or 11 capacitors.

• 1993–1994 LS400 ECUs commonly use 8 capacitors.

• 1992–1994 SC400 ECUs commonly use approximately 10 capacitors.

• One or more capacitors may remain unused, depending on the ECU circuit-board revision.

Open the ECU and record the capacitance, voltage rating, polarity, quantity, and location of every original capacitor before beginning the repair.

Common LS400 ECU numbers

Compatible ECU families may include, but are not limited to:

• 89661-50010

• 89661-50020

• 89661-50030

• 89661-50031

• 89661-50032

• 89661-50040

• 89661-50041

• 89661-50042

• 89661-50140

• 89661-50141

• 89661-50142

• 89661-50150

• 89661-50151

Common SC400 ECU numbers

Compatible ECU families may include:

• 89661-24230

• 89661-24231

• 89661-24240

• 89661-24410

ECU numbers vary according to production date, emissions specification, market, and traction-control equipment. These numbers are identification references and do not guarantee that every capacitor in the kit will be used.

Not compatible with

• Lexus SC300 2JZ-GE ECU

• Lexus LS400 or SC400 ECU versions outside the stated years without component verification

• Fuel-pump control modules

• Traction-control computers

• ABS control modules

• Transmission-only control modules

• Any circuit board whose capacitor values differ from the supplied kit

Separate capacitor kits may be required for 1995 and later vehicles.

Common capacitor-failure symptoms

Deteriorated or leaking ECU capacitors may contribute to:

• Intermittent crank/no-start condition

• Engine starting and immediately stalling

• Rough or unstable idle

• Hesitation or poor acceleration

• Intermittent misfires

• Sudden loss of engine power

• Poor fuel economy

• Erratic or harsh transmission shifting

• Engine or transmission failsafe operation

• Check Engine or TRAC warning lights

• Intermittent diagnostic communication

• Unrelated or inconsistent fault codes

These symptoms can also be caused by other engine, ignition, fuel, sensor, wiring, transmission, or control-module faults. The ECU should be properly inspected and diagnosed before repair.

Important repair information

Old electrolytic capacitors can leak corrosive and electrically conductive fluid onto the ECU circuit board. This leakage may damage copper traces, component leads, solder pads, and through-hole connections.

Replacing the capacitors will not by itself repair:

• Corroded or missing circuit-board traces

• Damaged solder pads

• Failed semiconductors

• Burned resistors

• Broken through-hole connections

• Water damage

• Previous incorrect repairs

Any leaked electrolyte must be thoroughly removed, and all affected traces and components must be inspected and repaired.

Installation warnings

• This is not recommended as a first-time soldering project.

• Disconnect the vehicle battery and remove the ECU before beginning.

• Use proper electrostatic-discharge protection.

• Photograph and document the original capacitor locations before removal.

• Verify every capacitor’s capacitance and voltage rating.

• Observe the correct positive and negative polarity.

• Installing a polarized capacitor backward can damage the capacitor and ECU.

• Avoid excessive soldering heat and prolonged contact with the circuit board.

• Inspect both sides of the board for leakage and corrosion.

• Clean the board using electronics-safe materials.

• Check for solder bridges and damaged traces before reinstalling the ECU.

Professional installation by an experienced automotive-electronics technician is strongly recommended.

Package contents

• One eleven-piece ECU capacitor repair kit

Engine ECU, solder, flux, cleaning supplies, tools, circuit-board repair materials, and installation service are not included.