Engine Cranks But Does Not Run. Cadillac Concours 1996

For 1990-2009 cars

### Circuit Description

The ignition system uses a waste spark method of spark distribution. During cranking, the Ignition Control (IC) module monitors the crankshaft position sensor signals. The signals are used to determine the correct pair to spark first. After the crankshaft position signals have been processed by the IC module, it sends a fuel control reference pulse to the PCM. When the PCM receives this pulse it will command all eight injectors to open for a priming shot of fuel in all cylinders. After priming, the injectors are left OFF for the next eight fuel control reference pulses from the IC module (two crankshaft revolutions). This allows each cylinder a chance to use the fuel from the priming shot. During this waiting period, a cam pulse will have been received by the PCM. Now the PCM begins to operate the injectors sequentially based on true crankshaft position. However, if the cam signal is not present at start-up, DTC P0340 will set and the PCM will start fuel delivery in a random pattern with a 1 in 8 chance that fuel delivery is correct.

The crankshaft position sensor signals are used only by the IC module. It is used for spark synchronization and to initiate reference pulses only (not passed to the PCM).

### Diagnostic Aids

Perform the A Powertrain On Board Diagnostic (OBD) System Check before performing this chart to help prevent mis-diagnosis.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check
2 | Are DTC(s) P0231, P0232, P0322, P0601, P0602, P1376, P1631, P1632 OR P1634 set? | -- | Go to DTC(s) that are set. | Go to Step 3

3

1. Install spark tester J 26792 on one spark plug wire and ground that cylinders companion cylinder plug wire.
2. Crank engine while observing the spark tester.
3. Repeat the above steps on at least one more cylinder.

Does the spark tester indicate a crisp blue spark on all tested cylinders?

--

Go to Step 4

Go to Electronic Ignition (EI) System Diagnosis (Ignition System Check)

4

1. Reconnect all plug wires.
2. Using a scan tool, command the fuel pump ON while listening for audible pump operation.

Was fuel pump operation heard?

Go to Step 5

Go to DTC P0231 Fuel Pump Feedback Circuit Low Voltage

5

1. Perform PCM Power And Ground Check. Refer to PCM Power and Ground Check (1 of 2) .
2. Perform Powertrain Ground Check. Refer to PCM Power and Ground Check (2 of 2) .

Was a repair to the vehicle made in either table?

--

Go to Step 11

Go to Step 6

6

1. Disconnect injectors number 1 and 3.
2. Install injector test light on both injector harneses and crank engine.

Do both injectors blink on and off?

--

Go to Step 10

Go to Step 7

7

1. Disconnect injector harness conector C127.
2. Using DMM J 39200 check voltage on terminals N and P (harness side)

Is the voltage the same or higher than the value specifed on both terminals?

10 volts

Go to Step 9

Go to Step 8

8 | Repair the injector ignition feed circuit(s) between C127 and fuse(s). Is repair complete? | -- | Go to Step 11 | --
9 | Replace PCM. Refer to PCM Replacement/Programming. Is the replacement complete? | -- | Go to Step 11 | --
10 | Perform Fuel System Diagnosis. Refer to Fuel System Diagnosis (Fuel System Check) . Was a repair made to the vehicle in the Fuel System Diagnosis? | -- | Go to Step 11 | Go to Step 12
11 | Does the vehicle now start and run? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | Go to Step 12
12 | Check for a mechanical condition that could cause a no start condition, for example a broken timing chain. Was a mechanical repair made? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | Go to A Powertrain On Board Diagnostic (OBD) System Check