Engine Cranks But Will Not Run - Isuzu 1999 RODEO Workshop Manual

Circuit Description
The electronic Ignition system uses a coil-at-plug method
of spark distribution. In this type of ignition system, the
powertrain control module (PCM) triggers the correct
driver inside the ignition coil, which then triggers the
correct ignition coil based on the 58X signal received from
the crankshaft position sensor (CKP). The spark plug
connected to the coil fires when the ignition coil opens the
ground circuit for the coil's primary circuit.
During crank, the PCM monitors the CKP 58X signal. The
CKP signal is used to determine which cylinder will fire
first. After the CKP 58X signal has been processed by the
PCM, it will command all six injectors to allow a priming
shot of fuel for all the cylinders. After the priming, the
injectors are left "OFF" during the next six 58X reference
pulses from the CKP. This allows each cylinder a chance
to use the fuel from the priming shot. During this waiting
period, a camshaft position (CMP) signal pulse will have
been received by the PCM. The CMP signal allows the
PCM to operate the injectors sequentially based on
camshaft position. If the camshaft position signal is not
present at start-up, the PCM will begin sequential fuel
delivery with a 1-in-6 chance that fuel delivery is correct.
The engine will run without a CMP signal, but will set a
DTC code.
Diagnostic Aids
An intermittent problem may be caused by a poor
connection, rubbed-through wire insulation or a wire
broken inside the insulation. Check for the following
items:
f Poor connection or damaged harness – Inspect the
PCM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wore connection, and
damaged harness.
f Faulty engine coolant temperature sensor – Using a
Tech 2, compare engine coolant temperature with
intake air temperature on a completely cool engine.
Engine coolant temperature should be within 10°C of
intake air temperature.
sensor.
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 Check the 15 A ignition coil fuse, the 15 A engine
device fuse, and the 15A PCM fuse.
Was a fuse blown?
3 Check for a short to ground and replace the fuse.
Is the action complete?
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Engine Cranks But Will Not Run

If not, replace the ECT
Engine Cranks But Will Not Run
Action
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
5. An obvious cause of low fuel pressure would be an
empty fuel tank.
6. The engine will easily start and run if a few injectors
are disabled. It is not necessary to test all injectors
at this time since this step is only a test to verify that
all of the injectors have not been disabled by fuel
contamination.
7. A blinking test light verifies that the PCM is
monitoring the 58X crankshaft reference signal and
is capable of activating the injectors. If there is an
open or shorted driver circuit, DTCs 201–206 and a
misfire DTC 301-306 should be set.
19.By using a spark tester, each ignition coil's ability to
produce 25,000 volts is verified.
25.If there is an open or shorted driver circuit, DTCs
201-206 and a misfire DTC 301–306 should be set.
All six injector driver circuits can be checked at one
time without removing the intake manifold if a J
39021-95 test light is available. This is the
alternative procedure:
f With the ignition "OFF," disconnect the gray
connector located at the rear of the air filter, attached
to a bracket on the purge canister.
f Connect test light J 39021-95 to the connector. Do
any of the light constantly illuminate or fail to blink
when the engine is cranked? If so, repair the short or
open circuit, or replace the PCM if indicated.
This procedure only tests the driver circuit as far as the
test connection, so step 31 is added to test the circuit all
the way to the injector.
Value(s)
— Go to Step 2
— Go to Step 3
— Verify repair
6E2–87
Yes No
Go to OBD
System
Check
Go to Step 4
—