Beretta L4-138 2.3L DOHC QUAD 4 (1991)
Please make a note of these revisions in your Service Manuals.
Diagnostic Aids
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A small amount of resistance in the Keep Alive Memory circuit may cause a no start with a functioning MIL. Check circuit J2-03 for resistance if
suspected of causing the no start condition.
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Check for TP sensor binding or sticking in Wide Open Throttle (WOT) position or intermittently shorted or open.
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Check "THEFT SYSTEM" telltale for flashing on the Instrument Panel Cluster (IPC) If Passlock System has been activated, refer to the IPC for
further diagnosis.
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Check for water or foreign material in fuel.
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Check for a basic engine problem (low compression, i.e., timing chain failure).
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Verify that only resistor spark plugs are used.
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A scan tool can be used to energize the fuel pump "ON" to check fuel pump operation and for ignition voltage at the injector harness.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
2.
Diagnosis of set DTC's may lead to the cause of the cranks but will not run complaint.
3.
PCM grounds will only cause a problem if all the grounds are not making a good connection. If a problem ground is suspected, the most probable
place to check is where all the grounds meet at the engine block.
7.
Locate and repair any shorts that may have caused the fuse to open before replacement.
8.
A TP sensor that reads too high can cause an incorrect fueling condition.
9.
An engine that has not been started recently should display ECT and IAT temperatures that are relatively close to each other. In warmer weather
the IAT readings may be slightly higher than the ECT readings.
10.
This step looks for a normal barometer reading and a change in MAP sensor values while cranking the engine. This step verifies the MAP sensor
can detect the change in the manifold pressure that occurs while cranking the engine. Compare any questionable barometer readings with readings
from another vehicle.
11.
While cranking the engine, the CKP Activity Counter (7X reference) should increment to 255 then rollover to 0.
12.
If the scan tool loses serial data only while cranking, the ignition switch is not sending voltage to the PCM while in the crank position.
13.
Check for possible voltage loss to the PCM including the ignition switch itself.
14.
Battery voltage should be available at the ignition feed terminal (L) of the ICM 11 pin harness connector, and the ground terminal (K), should be a
good ground.
17.
The CKP sensor core is a magnet, therefore it should be magnetized.
18.
The CKP sensor should output a voltage near 1100 to 1300 mV as the crankshaft turns. It is possible to trigger the ICM with a voltage as low as
200 mV. If no voltage is produced, a poor sensor connection or faulty sensor is indicated.
19.
The test light connected to B+ simulates a reference signal to the PCM. An injector test light can be installed and will blink for every other touch
of the test light if the CKP Activity (7X reference) circuit, the PCM and the injector driver are all functioning properly.
23.
If the test light illuminates while probing the CKP Activity (7X reference) circuit, the CKP Activity (7X reference) circuit is shorted to ground. If
the test light remains "OFF" and the CKP Activity Counter does not increment on the scan tool, the CKP Activity (7X reference) circuit is open. If
the CKP Activity Counter increments several counts when the Reference Low (cavity H) circuit is probed, the CKP Activity (7X reference) circuit
is shorted to voltage.
25.
Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.
26.
Battery voltage should be available at the injector ignition feed circuit whenever the fuel pump power feed circuit is switched "ON" and when the
