The PGM-FI Main Relay can easily be tested with a multimeter to see if it has failed (or not).
In this tutorial I'll show you how to test it in a step-by-step manner. With your test results you'll be able to find out if it's bad or not.
Contents of this tutorial:
- Symptoms Of A Bad PGM-FI Main Relay.
- PGM-FI Main Relay Pin Out.
- Where To Buy The PGM-FI Main Relay.
- TEST 1: Making Sure That Terminal No. 1 Is Getting 12 Volts.
- TEST 2: Making Sure That Terminal No. 5 Is Getting 12 Volts.
- TEST 3: Making Sure That Terminal No. 6 Is Getting 12 Volts.
- TEST 4: Making Sure That Terminal No. 2 Is Getting Ground.
- TEST 5: Making Sure The Fuel Injectors Are Getting 12 Volts.
- TEST 6: Making Sure The Fuel Pump Is Getting 12 Volts.
- More 1.6L Honda Civic Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El PGM-FI Main Relay (1996-1998 1.6L Honda Civic) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 1.6L Honda Civic CX: 1996, 1997, 1998.
- 1.6L Honda Civic DX: 1996, 1997, 1998.
- 1.6L Honda Civic EX: 1996, 1997, 1998.
- 1.6L Honda Civic HX: 1996, 1997, 1998.
- 1.6L Honda Civic LX: 1996, 1997, 1998.
- 1.6L Honda Civic Del Sol S: 1996, 1997.
- 1.6L Honda Civic Del Sol Si: 1996, 1997.
- 1.6L Honda Civic Del Sol VTEC: 1996, 1997.
RELATED WIRING DIAGRAMS:
- PGM-FI Main Relay Circuit Diagram (1996-1998 1.6L Honda Civic).
- 1996-1998 Fuel Injector Circuit Diagram (1.6L Honda Civic).
- Fuel Pump Circuit Wiring Diagram (1996-1998 1.6L Honda Civic).
Symptoms Of A Bad PGM-FI Main Relay
The PGM-FI Main Relay failure will generally cause one of three problems.
- An engine no-start problem.
- An intermittent engine no-start problem.
- An intermittent engine stall problem (the engine suddenly turns off).
It's only when the PGM-FI main relay fails completely that your 1.6L Honda Civic's engine will not start.
When the PGM-FI Main Relay fails intermittently, the engine will not start or suddenly turns off every now and then (but most of the time it starts and runs without any problems).
In the majority of the cases, the PGM-FI Main Relay failure has to do with it not being able to supply power to the fuel pump.
The hardest problems to diagnose are the intermittent stall and intermittent no-start problems. Why? Because the relay has to be tested while the engine is not starting.
Once the engine starts, testing the PGM-FI Main Relay doesn't do any good (since the relay is working and supplying power to the fuel injection computer, the fuel injectors, and the fuel pump).
PGM-FI Main Relay Pin Out
|PGM-FI Main Relay Circuits|
|1||White w/ black stripe (WHT/BLK)||12 Volts Input|
|2||Black (BLK)||Chassis Ground (-)|
|3||Yellow w/ black stripe (YEL/BLK)||12 Volts Output To ECM|
|5||Yellow w/ green stripe (YEL/GRN)||Ignition 12 Volts Input|
|6||Blue w/ white stripe (BLU/WHT)||12 Volts Input (Ign. Switch Start Position Only)|
|7||Yellow w/ green stripe (YEL/GRN)||12 Volts Output To Fuel Pump|
|8||Green w/ yellow stripe (GRN/YEL)||Fuel Pump Control Signal|
Where To Buy The PGM-FI Main Relay
Due to the fact that the PGM-FI Main Relay is a critical component of the fuel injection system of your 1.6L Honda Civic, avoid buying a cheap knock-off brand-X relay.
The following links will help you comparison shop for the Standard Motor Products and the original Honda Mitsuba relay:
TEST 1: Making Sure That Terminal No. 1 Is Getting 12 Volts
NOTE: If the engine in your Honda Civic (Civic Del Sol) starts, then you can conclude that the PGM-FI Main Relay is functioning correctly. The tests in this tutorial assume that the engine is not starting.
For our first test we're gonna' make sure that female terminal number 1, of the PGM-FI Main Relay's connector, is getting 10 to 12 Volts DC.
The wire that connects to female terminal no. 1 is the white with black stripe (WHT/BLK) wire of the connector.
Terminal no. 1 gets power from fuse no. 44 of the under-hood fuse and relay box.
We'll use a multimeter to make sure that it's getting 10 to 12 Volts DC at all times.
These are the test steps:
Disconnect the PGM-FI Main Relay from its electrical connector.
Place your multimeter in Volts DC mode.
Connect the black multimeter test lead to a good Ground point.
I recommend that you use a jumper wire to connect the black multimeter test lead to the battery negative (-) terminal.
Gently probe the female terminal labeled with the number 1 (in the photo above) with the red multimeter test lead.
Female terminal no. 1 connects to the WHT/BLK wire.
Your multimeter should register 10 to 12 Volts DC.
NOTE: You don't need to turn the key to the ON position, since power should be available at all times.
Let's find out what your test result means:
CASE 1: 10 to 12 Volts are present. This is the correct and expected test result.
Now that you've confirmed that power is present, the next step is to make sure that terminal no. 5 is getting power too. Go to: TEST 2: Making Sure That Terminal No. 5 Is Getting 12 Volts.
CASE 2: 10 to 12 Volts ARE NOT present. Check that you're testing the correct female terminal of the connector.
If you're still not getting 10 to 12 Volts, then your next step is to make sure that fuse no. 44 of the under-hood fuse and relay box is not blown.
If the fuse is blown, replace and repeat the test.