T5-aod Swap - No Fuel Pump Prime

[1990Coupe]

I have done a search, and read lots of check lists and i'm stumped. My wiring must be wrong somewhere and im hoping someone can help.

Scenario is car is an 89 LX 5 speed 5.0. Car ran find when taken apart. We pulled the motor to change all the seals, and we installed an AOD. I plugged the AOD harness into the body of the car, disconnected the 2 plugs for the clutch switch and jumped 1 of the plugs with the 2 red/lt blue wires. Also there was a remote start which i unwired and re-connected the wires that were cut. The only other 2 things done were a heater core, and a 130amp alternator.

After installing the engine and trans, car will tun over, but no fuel pump prime.

I checked through this thread for testing proceedures: https://www.stangnet.com/mustang-forums/threads/no-fp-prime-no-koeo-light.897747/#post-9048307

In this thread, at this point i see 3 volts at the tan/lite green wire, NOT less then .75 volts. Jumping pin 22 and i do have a glow. However when i put the computer in self test mode to dump codes, the light does not flash.

The Tan/Lt Green wire provides a ground path for the relay power. With the test connector jumpered to ground, there should be less than .75 volts. Use a test lamp with one side connected to battery power and the other side to the Tan/Lt Green wire. The test light should glow brightly. No glow and you have a broken wire or bad connection between the test connector and the relay. To test the wiring from the computer, remove the passenger side kick panel and disconnect the computer connector. It has a 10 MM bolt that holds it in place. With the test lamp connected to power, jumper pin 22 to ground and the test lamp should glow. No glow and the wiring between the computer and the fuel pump relay is bad.

Also, i played swaptronics and swapped in another A9L computer - same thing. so i know its my wiring or something somewhere. Any help would be great cause i'm at a complete loss

 

[1990Coupe]

One more thing to add - i can get the pump to kick on by jumping the orange/lite blue wire and pink wire. But the car still doesn't fire. I'm getting a noid light Monday to check injector pulse to see if we're even getting a signal there. I looking at the circuit, i dont think that plugging the auto trans harness into the Manual car would have hurt anything. I have read that if i swapped the 02 harness from an AOD car into the manual car with the A9L computer, it would fry.

 

[jrichker]

Will the computer dump codes?
Dump codes sticky

Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. Codes may be present even if the CEL (Check Engine Light) isn’t on. You don’t need a code reader or scanner – all you need is a paper clip, or if your lady friend has a hair pin, that will do the job.
I highly suggest that you read it and follow the instructions to dump the codes. http://www.stangnet.com/mustang-forums/threads/how-to-pull-codes-from-eec4.889006/

If not you have computer of wiring problems.

 

[1990Coupe]

@jrichker no, codes were not dumping at all. Check engine light just remained illuminated. I'm going to undue the wiring mods i made, plug the clutch switch back in, and see if i can then at least dump codes. No other mods were made other than plugging in the transmission harness, and bypassing the clutch NSS switch. I'll report back if anything changes.

 

[jrichker]

Computer will not go into diagnostic mode on 86-90 model 5.0 Mustangs

Disconnect the battery positive terminal before making any resistance checks.
The voltage drop in the ground cable will cause incorrect resistance readings.

How it is supposed to work:
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the computer into self test mode. If this ground is bad, none of the sensors mentioned will work properly. That will severely affect the car's performance. You will have hard starting, low power and drivability problems. Since it is a dedicated ground, it passes through the computer on its way to the computer main power ground that terminates at the battery pigtail ground. It should read less than 1.5 ohms when measured from any of the signal ground connections to sensors on the engine harness. Use the battery pigtail ground as the other reference point for the ohmmeter probe.

What sometimes happens is that the test connector black/white wire gets jumpered to power which either burns up the wiring or burns the trace off the pc board inside the computer. That trace connects pins 46 to pins 40 & 60.

The STI (Self Test Input ) is jumpered to ground to put the computer into test mode. Jumpering it to power can produce unknown results, including damage to the computer. The ohm test simply verifies that there are no breaks in the wiring between the test connector and the computer input.

How to test the wiring :
With the power off, measure the resistance between the computer test ground (black/white wire) on the self test connector and battery ground. You should see less than 1.5 ohms.

If that check fails, remove the passenger side kick panel and disconnect the computer connector. There is a 10 MM bolt that holds it in place. Measure the resistance between the black/white wire and pin 46 on the computer wiring connector: it should be less than 1.5 ohms. More that 1.5 ohms is a wiring problem. If it reads 1.5 ohms or less, then the computer is suspect. On the computer, measure the resistance between pin 46 and pins 40 & 60: it should be less than 1.5 ohms. More that that and the computer’s internal ground has failed, and the computer needs to be repaired or replaced.

See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix for the computer internal signal ground.

If the first ground check was good, there are other wires to check. Measure the resistance between the STI computer self test connector (red/white wire) and pin 48 on the computer main connector: it should be less than 1.5 ohms. More that 1.5 ohms is a wiring problem

The following is a view from the computer side of the computer wiring connector: it is for an A9L, A9P computer.

Diagram courtesy of Tmoss & Stang&2birds

Check out the diagram and notice all the places the black/white wire goes. Almost every sensor on the engine except the MAF is connected to it.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine

See the graphic for the 10 pin connector circuit layout.