Total MX-5 – July 2019

LIGHT, HEAT AND WINDOWS

Michael Cleverley of Cleverley Repaired Cars, expert on all things MX-5, answers your questions

TURN THE LIGHT OUT

Q

My early mk2 has failed its
MOT because the ABS light
is on. Can you tell me how to
diagnose the fault so that I can
fix it please?

A

Being an early mk2 you do
not have an EOBD socket
that you can plug a code reader
into. Instead these cars give out
blink codes similar to mk1s.
To read the blink codes you
must lift the bonnet and open
the diagnostic box on the inner
wing. Using a piece of wire,
bridge the TBS and GND pins.
Turn the ignition on and
observe the ABS light on the
dashboard. It will be flashing for
long and short periods. A long
flash equals 10 and a short flash
is 1. If you miss it don’t worry as
after a pause it starts again.
An internet search will give
you a key to the blink codes. For
example, one long flash and
two short ones make 12,
meaning the left front wheel
speed sensor or its wiring is
faulty. To confirm the fault,

[ Q&A ]

76 | TOTAL MX-5 |^ Summer 2019

unplug that sensor and insert a

1K ohm resistor into the harness.

Next clear the codes – remove

the wire bridge you inserted in

the diagnostic box, disconnect

the battery and apply the brake

for about 30 seconds. If not,

suspect faulty wiring or the ABS

module (not common).

Otherwise a new sensor should

do the trick. The old sensors are

notoriously hard to remove,

often needing to be broken up

to get them out.

Above: Left front wheel sensor

found to be at fault, causing ABS

light to come on. Below: Bridging

the TBS and GND pins in the

diagnostic box to activate blink

codes via the ABS light

HOT FLUSH

Q

My mk1 1.8’s heater isn’t

very good. Turned to hot it

gives out some warm air but

never gets really hot. Otherwise

the car runs well, although

maybe the fuel consumption is

slightly high. Can you give me an

idea what to look for please?

A

This problem could have a

few causes. If the engine

gets up to correct running

temperature quickly and stays

there, then the likely problem is

a silted up heater matrix. You

can attempt to flush this out by

removing the heater hoses

(carefully as the metal pipes

through the bulkhead near the

cylinder head are made of very

soft brass and easily distort).

Use a hosepipe to flush the

matrix with water. If you’re

lucky you may see dirt coming

out of the matrix and your

problem will be solved.

The other common problem

is a thermostat that is stuck

open preventing the engine

from reaching full running