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Car Forum / Mitsubishi Cars / July 2008Ignition key (?) relay location? (89 Mirage)
We have here a 1.5L 89 Mirage with manual transmission. According to a diagram I found, there is a relay between the ignition key and pin 7 of the main/ECU relay (you know, the one which is under the center console). Where is this starter relay (for a lack of a better term) and how is it turned on? > ... there is a relay between the ignition key and pin 7 > of the main/ECU relay There's a bunch of relays above the brake pedal. The MPI relay (center console as you describe) is powered by the IGN switch. The intermediate relay may be the problem, but more common is the MPI relay develops an internal problem and the IGN switch does not enable it. The MPI relay does several things: 1. It provides +12v to the ECU (hence running ECU and hence the injectors) 2. It provides +12v to the fuel pump. Check with your meter for an enabling +12v on the MPI relay when the IGN switch is at ON and START positions. Check for output of +12v on the MPI relay. You should hear or feel the relay activate. Its possible to remove the relay cover to check the internal operation. The common problem is corrosion of the relay activation wire, and usually easily fixed. You can also check the ECU diagnostic port for any error codes. Get a +12v LED or an analog multimeter. Measure across the diagonal port pins. One setting will light the LED or swing the meter needle. Normal ECU operation outputs a continuous stream of short pulses, about 2 Hz. A long pulse = 10, short pulse = 1, so 2 short + 4 long = error code 24. No pulses or the LED always on indicates a dead or unpowered ECU.  Signatureregards Stewart DIBBS www.pixcl.com/lancerproject > > ... there is a relay between the ignition key and pin 7 > > of the main/ECU relay [quoted text clipped - 7 lines] > 1. It provides +12v to the ECU (hence running ECU and hence the injectors) > 2. It provides +12v to the fuel pump. So, it is like the main switch in a Honda. Incidentally, I took the relay out and tested it by running power between pins 6 (GND) and 7 and then checking for continuity on pins 1 and 4. Nothing. > Check with your meter for an enabling +12v on the MPI relay when the IGN > switch is at ON and START positions. That was my next step: I took the relay out (eliminate that variable and test the circuit before it) and checked the pin 7 in the connector for power when the IGN switch was at ON (pins 3 (12V) and 5 (GND)) and START (pins (7 (12V) and 6 (GND)) positions. There was none. Looking at the circuit below, http://kudria.com/projects/vehicles/mitsubishi/images/89MirageFI-sm.jpg I thought the culprit would be somewhere between that connector and the ignition switch. But, the problem is where these parts (blue, green and red in the schematics) hide. > Check for output of +12v on the MPI relay. You should hear or feel the relay > activate. Its possible to remove the relay cover to check the internal > operation. The common problem is corrosion of the relay activation wire, and > usually easily fixed. That was my first step. Once I did not hear it click or detect the voltage on pin 1, which should have taken place if the key was in the START (voltage flowing through pins 6 and 7) or ON (voltage flowing through pins 3 and 5, but only if MPI detects that the engine is firing). I had no voltage on pin 1. Which is why I then checked the relay out of the car and then for voltage on pins 7 and 3. > You can also check the ECU diagnostic port for any error codes. Get a +12v > LED or an analog multimeter. Measure across the diagonal port pins. One > setting will light the LED or swing the meter needle. Normal ECU operation > outputs a continuous stream of short pulses, about 2 Hz. A long pulse = 10, > short pulse = 1, so 2 short + 4 long = error code 24. No pulses or the LED > always on indicates a dead or unpowered ECU. I will try that next. Thanks for all the help! > -- > regards > Stewart DIBBSwww.pixcl.com/lancerproject > ... there is a relay between the ignition key and pin 7 > of the main/ECU relay There's a bunch of relays above the brake pedal. The MPI relay (center console as you describe) is powered by the IGN switch. The intermediate relay may be the problem, but more common is the MPI relay develops an internal problem and the IGN switch does not enable it. The MPI relay does several things: 1. It provides +12v to the ECU (hence running ECU and hence the injectors) 2. It provides +12v to the fuel pump. Check with your meter for an enabling +12v on the MPI relay when the IGN switch is at ON and START positions. Check for output of +12v on the MPI relay. You should hear or feel the relay activate. Its possible to remove the relay cover to check the internal operation. The common problem is corrosion of the relay activation wire, and usually easily fixed. You can also check the ECU diagnostic port for any error codes. Get a +12v LED or an analog multimeter. Measure across the diagonal port pins. One setting will light the LED or swing the meter needle. Normal ECU operation outputs a continuous stream of short pulses, about 2 Hz. A long pulse = 10, short pulse = 1, so 2 short + 4 long = error code 24. No pulses or the LED always on indicates a dead or unpowered ECU. Signatureregards Stewart DIBBS www.pixcl.com/lancerproject |
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