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AE86 16V - Diagnostic Plug and FP Test Plug

Posted: Tue Apr 29, 2014 1:40 am
by jondee86
On earlier years of the AE86 the diagnostic plug is a round, yellow two-pin
female plug found hanging off the engine bay harness by the AFM. The other
yellow "T-shaped" plug is the Fuel Pump test plug.

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Some later model cars have a small black multi-pin diagnostic box hanging
off the firewall. The diagram inside the cover will identify the pins.

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You will need to know where to find the diagnostic plug on your car if you
want to check for trouble codes or set the ignition timing. In the diagnostic
box the pins to short are T and E1.

To force the Fuel Pump to run for trouble shooting purposes, short (jumper)
the T-shaped FP test plug with a piece of wire, and turn the ignition switch ON.
A male spade connector on either end of a small piece of wire will make a good
jumper wire. In the diagnostic box the terminals to short are FP and B+.

Do not drive your car with the FP test plug shorted. This procedure bypasses
an important failsafe feature, and will put you at risk if you have an accident
or engine bay fire.

Cheers... jondee86