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Error codes Weber Marelli ECU P8 & L8
Even though the IAW048 system from
Weber-Marelli is an old and supposedly outdated control unit, it still has a lot of features to offer.
The built-in Motorola processor was a modern component in the 80s of the last millennium :-) that doesn't have to hide even today.
In addition to a data stream that can output all data read in from the sensors live to the diagnostic interface, there is also the option of activating a slower data output for a blink code.
Since this is the easiest way for many DIYers to find a fault, I will go into it in more detail here.
To activate the error code output, the diagnostic connector must first be located.
In the Escort Cosworth with standard wiring harness, it is hidden in the engine compartment on the front left dome.
Depending on the model, there are 2-3 free plugs with cover caps here. For the error code on the Weber-Marelli system, we need the plug with the following cable colors:
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Brown/green -Ground Pin11
Blue/white - Pin8
Blue/yellow - Pin27
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Caution, picture from HTT
different plug shape for W/M!
In vehicles with aftermarket wiring harnesses, the connector is often located near the control unit connector.
(3-pin Superseal connector)
Check assignment with measuring instrument!
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Now we connect a small automotive test lamp or an LED with a suitable series resistor for 12V to the blue/yellow cable, the other side of the lamp is connected to a +12V source, the easiest way is directly to the battery. (Note the polarity of the LED!)
The brown/green and blue/white cables must be bridged with a piece of wire.
Then switch on the ignition, do not start the engine.
Now the lamp starts to flash:
At first it is very fast for 2 seconds, then it goes out.
From now on, the error code appears every second:
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In this example, first 3x 1s each, then 3s pause, then it lights up again 2x and again 3s pause.
In this example we have error code 32.
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One code after the other is issued, then it starts again from the beginning.
The error code output can be interrupted by turning off the ignition.
1.1 = Crankshaft sensor error – check sensor, wiring, air gap (0.8mm)
1.2 = Phase sensor error – check sensor, wiring, air gap (0.7mm)
1.3 = Crank/phase sensor pulse pattern error –
Check sensors, wiring, air gap, mount, distributor position
2.1 = Charge air temperature sensor - short circuit or open circuit - check sensor and wiring
2.2 = Knock sensor error – check sensor and wiring
2.3 = Water temperature sensor - short circuit or open circuit - check sensor and wiring
3.1 = Lambda sensor error – check sensor, wiring, for leakage air
3.2 = MAP sensor short or open circuit – check sensor and wiring
3.3 = Throttle position sensor short or open circuit – Check sensor and wiring
4.3 = internal ROM error (P8 only)
4.4 = Checksum error (P8 only)
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To make it quick and easy , I built a simple diagnostic cable for flashing with an LED and a suitable plug.
Fits all Sierra and Escort with Weber Marelli control:
