LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2004 >> Swift + >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.6L (L91) Troubleshooting & Diagnosis) >> Troubleshooting >> Fuel Injector Circuit Diagnosis >> Diagnostic Aids
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Aids

Fuel Injector Circuit Diagnosis

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 Is DTC P0201, P0202, P0203, or P0204 set? - Go to DTC P0201-P0204 Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the fuel injectors.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of a fuel injector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
- Go to Step 4  Go to Step 11 
4
  1. Remove the fuse for the fuel injector ignition 1 voltage circuit.
  2. Measure the resistance from the fuse to the ignition 1 voltage circuit terminal of a fuel injector with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance more than the specified value?
3 Ω Go to Step 12  Go to Step 5 
5
  1. Install the fuse for the fuel injector ignition 1 voltage circuit.
  2. Connect the J 34730-405  Injector Test Lamp into each injector connector one at a time.
  3. Crank the engine.
Does the test lamp flash brightly for each injector?
- Go to Intermittent Conditions  Go to Step 6 
6 Does the test lamp remain illuminated at all times for any injector circuit? - Go to Step 8  Go to Step 7 
7 Test the control circuit of the affected fuel injector for an open and for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 15  Go to Step 9 
8 Test the control circuit of the affected fuel injector for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 15  Go to Step 14 
9
  1. Disconnect the engine control module (ECM).
  2. Measure the resistance on the affected fuel injector control circuit with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance more than the specified value?
15 Ω Go to Step 13  Go to Step 10 
10 Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 15  Go to Step 14 
11 Repair the open in the ignition 1 voltage circuit of the fuel injectors. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 15  -
12 Repair the high resistance in the ignition 1 voltage circuit of the fuel injectors. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 15  -
13 Repair the high resistance in the control circuit of the fuel injector. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 15  -
14 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?
- Go to Step 15  -
15 Operate the system in order to verify the repair.
Did you correct the condition?
- System OK Go to Step 2