The main task
of the Main Relay is to supply power
to the fuel pump and fuel injection system.
Some of the symptoms
are:
- Car won't start when hot outside
on fuel injected models.
- Car does not
start after parked
for just a minute.
- Car starts
but quickly dies.
- Windows have
been rolled up on a hot day when problem occurred.
- The heater
was on before turning the car off.
- Tapping your
finger or keys on the main relay will start
the car.
- No sounds
from the fuel pump in the fuel tank initially.
- Check engine
 light comes
on or stays on longer than usual or
- 10-15 of
waiting and car pushed to a shade, will start
Accord Main Relay
REMOVAL
90-93 Accord's relay location/repair
procedure:
  
The main relay is located
behind the dash on the driver side to the left of the steering column.
It is hidden above the silver cruise control box. After removing
the cruise control box, you should see the main relay with a gray
and rosy colored base.
- Remove the cruise control box
using a 10 mm socket
- Remove the relay
- Squeeze in the connector lock
and
- Unplug the connector from the
relay
- Installation is the reverse of
the procedure, although it isn't require to bolt it back at its
original spot. Move the relay to a low, suitable spot where it
is cool and away from heat vents.
86-89 Accord's and some
Acura Integra
relay location/repair procedure:
The main relay is located
just right above the hood release, inside the dash panel bolted
to the left kick panel with a bolt that will fit a 10 mm socket.
It has seven wires from the connector.
- Remove the coin box (for clearer
view)
- With a 10 mm socket or wrench
- Reach deep inside and at the top
of the relay there you will feel a bolt.
- Unbolt it.
- Bring the relay down and unplug
the connector by squeezing the lock flap and separate the connector
from the relay.
- Installation is the reverse of
the procedure, although it isn't require to bolt it back at its
original spot. Move the relay to a low, suitable spot where it
is cool and away from heat vents.
Civic Main Relay
REMOVAL
The 85-95 Civics
is also located in the same general area as the
Accords. Older Acura Legends is located behind the fuse panel near
the firewall.
The
color of the relay is usually black with a brown base. The wires
coming from it are usually seven. It's above the hood latch release
to the right and very high up. Removing it requires removing several
parts surrounding it.
The relay is made
up of two relays, one for the fuel injection system and one for
the fuel pump. The relay sits on a PC board inside a plastic case,
The PCB board contains resistors and some diodes. The common heat
build up is the fuel pump relay, which causes an expansion and contraction
of the solder joints thus creating an environment for drying and
cracking.
Usually the fuel injection system relay may be the second to fail.
If the fuel injection relay fails, a "check engine light"
will signal a warning and a code may be sought. The code should
point to a fuel injector problem.
There have been reported
cases of 88-91 Civics where no sparks have been found due to a bad
main relay. It is possible that the ECU plays a part in the ignition
system but this is not possible after examining the Civic's wiring
diagram. On years 1992 and up, the ECU manages the sparks.
A bad relay usually produce no spark on these models.
INSTALLATIONS
- Installation
is the reverse of the procedure.
- It
is not required to install into its original location. Move it
to a cooler location. Eg., away form heat ducts or higher locations.
And future troubleshooting would be far easier.
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