Code 96 Repair:

[FoMoCo17]

Got a code 96 on a 1990 Mustang GT. Replaced the fuel pump relay and got the pump from running on continuously. But, for some reason, I keep getting the Code 96 after wiping the memory. Checked wires on secondary circuit. In the process of replacing the EEC relay. All wires on relay read battery/alternator voltage as they should and Pin 19 reads the same so I am unsure what is causing the problem. The tan/green wire that goes to Pin 22 is reading 1.40 volts at the fuel pump relay and 1.15 volts at ECU Pin number 22 ... this doesn't seem right from what I have read. Also, the car seems like it is down on power but also had a bad heater core which I am replacing. The Code 96 started after I was scanning the engine and disconnected one of the salt & pepper connectors to check for a problem while the code scanner was still hooked up. Yes, I know ... mistake. Anyway, when I reconnected the connector, the fuel pump kicked on and would not shut off so I had to pull the battery cable and then replace the fuel pump relay. It was after this, that I have repeatedly gotten the code 96.

Any suggestions are exact information would be helpful since I'm quite tired of tearing the car apart and searching and not finding anything. Possibly, JRickter can help me on this one since I have read everything on the internet including his help with other technical problems. So, what is causing this???

 

[FoMoCo17]

Anyone have any expertise in this area?

 

[hotcobra03]

how about your grounds?

eec ground to battery ground?pin 40/60

 

[jrichker]

Code 96 – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump lost power at some time while the ignition switch was in the run position.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the Mass Air Meter on Fox bodied stangs built after 91. On earlier model cars is under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly. See Mustang Mass Air Conversion «

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.

86-90 Models:
Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump is the likely culprit since it is getting power. No voltage there, check the Orange/Lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

 

[FoMoCo17]

Thanks Jrichker,

I have checked pretty much all of this. The car is sorta apart right now getting it ready for the show season. I just replaced the ECM relay, this could be the problem since the fuel pump relay was definitely a problem. Really won't know for sure until I get the car out on the street within 2 months ... just wanted to check or eliminate, or solve the problem so it doesn't crop up again.

Fuel pump is 2 years old. The grounds 40 & 60 are mentioned, do they come into play here and how can they be specifically be checked. Multimeter across the battery and each pin (one at a time) with ignition on or while pump is operating? And, does the 1.45 volts on the tan/green wire at fuel pump relay seem like it could be impacting this problem since it is supposed to be the ground for the primary side of the fuel pump relay? I have checked every other ground on this car except Pin 40 & 60.

Any other ideas would be quite helpful. As I said, it seems like the car is down on power just a tad maybe 10 % ... just is weird. Would like to find it before putting the car back on the street since it was quite annoying last summer!

 

[FoMoCo17]

To clarify:

This appears to be an intermittent problem since the code is not always set right away when the car is running. It apparently crops up after a days driving but no noticeable effects while driving other than possibly a slight lack of power. Thus, test readings always look good other than the tan/green wire reading that always reads the 1.45 volts @ the relay or 1.15 volts @ pin 22.