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Bosch Motronic M1.5.4


bosch motronic m1.5.4

Components description

  1. Main relay – regulator 5v
  2. Injectors
  3. Idle speed
  4. Ignition coil
  5. Ignition coil
  6. Detonation


Vehicle does not start

This problem can be caused by the malfunction (breakdown) of the 5V Regulator, the unit does not light up the anomaly lamp, does not activate the pump relay, on the bench (ECU-TEST) it will only indicate the ECU Mass, as this regulator feeds the entire the internal circuit of the ECU, without power to these components the system will not operate. Solution, replace the 5V Regulator.

Injector nozzles (electro-valve)

Injector nozzles do not pulse, or are 'stuck', short-circuited, or even open', do not pulse in the Vehicle, or even on the Bench; when using ECUTEST. In the specific case of the ECU Test, a Universal Symptom (that is, for all ECUs) regarding ‘stuck nozzles’; This UCE Simulator may present two situations: the Indicator LEDs (of the Injector Nozzles), lit constantly, that is, without pulsing and intensely (referring to luminosity), or they may appear 'half-light', as if they were 'half off'. In both cases, we determined with certainty that there is a fault related to the Injector Nozzles in the Control Unit. The solution is to replace the Multidriver that controls the 04 Injector Nozzles.

Vehicle does not come into operation, and UCE does not work on Bench

(Universal Standard for all UCEs) This is due to the Burning of the Mass (-) of the Central, generally caused by broken tracks in the Circuit, or even broken terminals that are interconnected to the ECU mouthpiece. This defect occurs mainly due to some type of Overload, (or Voltage Peak, either generated by the Alternator, which is working outside its Standard Working Voltages, or due to some Polarity Inversion, either in the Vehicle Battery poles). , due to the so-called 'Inverted Pacifier' on the (+) and (-) Poles; or due to a Short Circuit in the Electrical Wiring of the car itself or even in the Vehicle's Sensors or Actuators), or in another existing possibility; , due to a Short Circuit connected to Ground (-), or Ground, of both the Sensors and the Main Ground (-) of the ECU itself.

Ex: In the specific case of the Vectra, when the Grounding of the Engine Starting, the Mass(-) is poorly connected, or even disconnected, generally causes the Burning of the Central Mass. The Solution for The problem is to redo the burnt trails, by using a Perfect Stock Center (preferably with the same number) and then testing; the vast majority of the time it works. Otherwise, that is, if the Reconstitution of the Trails does not solve the problem; Enter the Oscilloscope, preferably Digital, into the Eprom Memory of the ECU, the Memory will be pulseless (that is, it will not be working with a Working Voltage applied to the Eprom Memory, which must vary between 0.3 and 0 .5 V to 3.3 and 3.5 V, or even from 4.3 to 5 V, in the measurements carried out). If this happens, that is, it does not present the oscillation between the expected working voltages; The solution is to exchange or replace the Microprocessor, which works together with the UCE Oscillator Crystal.

IMPORTANT: When using a Digital Oscilloscope, or even an Analog Oscilloscope, if you prefer the latter, greater knowledge in Electronics is required for this Procedure to Operate the Equipment.

ECU Power Loss (Line 30)

Due to Track Heating, probably generated by a short, the ECU loses the 12 V Power Supply, or Line 30, coming directly from the Battery. The Solution in this case is to Redo the broken Original Tracks, mapping them according to a Stock ECU (with the same number as the damaged Central), and in perfect condition and good functioning; So, follow the broken trail and retrace it according to the original.


Vehicle has no spark in the Ignition Coil; or Ignition Coil with direct and continuous sparking (commonly called 'Ignition stuck'), or very weak Ignition Coil pulse, the latter defect, which will prevent the Vehicle from starting or starting.

Ex: One time the first Ignition Drive, which controls Cylinders 01 and 04, 'roasted'. It burned in such a way that it almost fused the Plate's aluminum heat sink with the Ignition Drive housing, also destroying the Plate Tracks . This was due to a Short Circuit in the Ignition Coil of a Kadett, which possibly received a 'reversed charge', thus causing such damage. The solution in this case was to replace the Ignition Drive, a Darlington Transistor (encapsulation, or component format), and then redo the Tracks, based on another Stock ECU in Perfect Condition.

There is also the possibility that one of the 02 SMD C.I.s (Integrated Circuits of) Ignition Controllers (of which 01 of them is also responsible for the Pulse to the Pump Relay, are not sending the Ignition Pulse to the Drive(s) of Ignition, something estimated in the range of 0.3 to 0.5V, since the 02 Transistors, are Transistors that amplify the Ignition Signal sent by such C.I.s, which will allow these Transistors to generate or not, the Spark in the Coil. Vehicle ignition. Solution in this case: Replace the Ignition Pulse C.I.(s), if the Ignition Drivers (Transistors) have already been Measured and Replaced, and the problem has not been resolved.

Vehicle does not start, does not activate the Pump Relay.

Vehicle does not start, does not activate the Pump Relay, the Vehicle Anomaly Lamp flashes and does not start. The Defect is related to 02 Brown (Light) or Dark Beige “Capacitors”, which have 01 Black or Blue ‘Resistor’, right in the middle of them (capacitors); on the other side of the Board of this UCE M 1.5.4, which are located right in front of the ‘tip of the Soldered Terminals’ of the Multidriver of the 5V Regulator/Main Relay (as shown in the mapping in the photo above).

Idle Oscillation

Vehicle oscillates at idle speed, not allowing adjustment, or vehicle works 'with excess' fuel, after the Sensor has already been checked (Stepper Motor in the vehicle, or in a situation that requires even more testing, replace the Sensor: Stepper Motor I go through a new one, in the vehicle).

Vehicle won't start, or Malfunction.

Vehicle does not start, or works with difficulty (which will largely depend on the state of the Vehicle Rotation Sensor); or the Fault may be found in the ECU Drive that works this Rotation Signal, an SMD C.I., of the Rotation Signal, located right in the center of the Board of this ECU M1.5.4. Solution: If you have already tested another Rotation Sensor in the car, there is also a Universal Tip for defects in the Injection System of all Vehicles: considering that in many cases, when we measure basically any Sensor, trying to find the Standard Voltage Readings, NOT ALWAYS when we find the specified Measurements, in the Tests of the Electrical Diagram Tables, can we really ACTUALLY trust that such Sensor, (in this specific case, the Rotation sensor), is in Perfect Working Condition. Because such measurements presented by the Sensors (in a Rest State, can MANY times prove to be misleading, that is, because they are not working energized.

Ex. in this Specific Case:

(Presented in the Measurement Table) Electrical Diagram:

Rotation and PMS Sensor:

Pins 48 - 49 (continued..)

Resistance (OHMS) 800 to 1200

Therefore, in this specific case, replace the Engine Rotation Sensor Vehicle, for a new one, and take the Test. If the problem persists, replace the SMD C.I. that handles the Rotation Signal in the ECU.

Universal Tip for ALL Control Units:

Obviously, before carrying out any repair on the ECU, or even before opening it, simulate it in the ECU Test first, of course. After that, the Tip regarding the topic above is: Please ALWAYS check the ECU Memory Eprom, when you have doubts as to whether the Unit is in good condition or not. BEFORE carrying out any Repair on the ECU, or even after ALL repair attempts have been made on the ECU. Because the Eprom Memory File may become corrupted or the Eprom Memory (Chip in DIP, PSOP, PLCC, TSOP format or another type) may burn, thus causing the ECU to NOT FUNCTION. In this case, check the model of the Eprom Memory, record another one using the Original File, or even the File preferred by the ECU owner, or Vehicle.



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