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Discussion Starter · #1 ·
I recently (less than 6 months) swapped over the motor, trans, rear end, gas stuff, brakes, springs, interior and so on from my 88 convertible into an 89 GT and converted it from auto to manual. I left the A9P (auto computer) computer in there and fired the car up. It runs great and idles great about 95% of the time, never stalls.

I recently ran into problem of my TP sensor losing its ground somewhere , so I ground it myself and it took care of it. This is a side note but it would dump so much fuel that the spark plugs would foul and I cant start the car.

I know my code reader works and it refuses to work with keys on engine off and keys on engine running.

Any ideas why or something I might of missed during the swap? When I hook the code reader up I can hear my relays click over and fuel pump prime but nothing ever comes out. Car runs great except a little rich (13 mpg city).
 

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recheck your grounds on the motor..........engine to frame, engine to body, etc.........see what happens.........hotwheels of turborides
 

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Your CPU will not send codes unless the trans is in neutral (5spd/auto) or in park (auto).

You said you converted from auto to manual. Did you replace the wire harness that runs under the driver’s side carpet? It runs from the D/S kick panel, under the carpet and out the trans tunnel. There is a difference between the manual harness and the auto harness. The manual harness has the wiring you need to complete the circuit that tells the CPU the trans is in neutral. Also up under the dash there are some jumper wires that need to be replaced when you do this swap.

With a wire diagram you can jump this circuit at the kick panel to get the codes to be sent.
 

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Discussion Starter · #4 ·
All I did was attach the manual transmission harness (from the other car) that plugs into the where the old neutral safety switch.

Are there any other effects that I could be experiencing by the computer not ever knowing it's in neutral ?
 

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I don't believe so. It is an open ciruit most of the time. It is only closed when in neutral. The circuit is there for safety reasons. You know, make sure the trans is in neutral, block the tires. The basic safety issues when working on a car.
 

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I've wondered about EEC and the neutral switch. Did you wire in the clutch
switches (one for the start circuit, one for EEC)? If so, try scanning with your
clutch pedal pressed to the floor(from the time you turn the key on till it spits
out the codes - I always kept it down till the last code). The junk '87 T5 that
came in my '92 had the neut switch wires cut too close to the switch, so I
wired it so that the car thinks it's always in neutral. I hooked a test light to my
spare T5's neut switch, and rowed through the gears, and the light flashed
during every shift as it went through neutral between gears. So on a stock 5
speed car, EEC should be aware of every time the clutch is depressed, and
time the tranny is shifted. Dunno if it acts on this info. Compare the pinout
diagrams between your A9P and an A9L, this may shed some light on your
setup. Mine would give me the KOEOs and Continuous Memory codes with
the neutral circuit open, but no KOERs. 67-KOEO is an open neutral circuit.
 

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Manual/Automatic EEC Code Wiring Differences

There is a hardware difference between an auto processor & a manual processor. The difference is because of the way the NDS [neutral drive switch, manual trans] & the NSS [neutral safety switch, auto trans] are wired. They are both wired to the same pin#30 but the auto trans wiring grounds the pin to the starter solenoid & the manual grounds to signal return, during crank mode there is a voltage spike sent to pin-30 so the auto trans processor has a diode on pin 30 where as the manual processor doesn't, most of the time this won't cause a problem unless you get into a prolonged crank condition.

I've been warning people about converting an auto to a mnual and using the manual EEC with the auto wiring harness; those that want to convert their automatics to manuals, and swap the ECM, need to clip the wire going to pin 30 or else the ECM will fry.
 

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Discussion Starter · #9 ·
Good to know Tom. I've been swamped with homework and studying for finals these past weeks so I will finally be able to get under the car and give a good look at things.
 

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What frys on the EEC is the ground trace for the "signal return". Since it's at ground potential, you might get it fixed by soldering a wire bridge over the burned trace if it hapopens to anyone.
 
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