93 LX 2.3 Trouble codes 53, 85, 21 help

Hi, I can't resolve these codes after running KOER (warm engine), even after swapping in a spare F1ZF-AB ECU.

Start with 85 canister purge solenoid. Solenoid is not fauty, switches with 12v to ground test. There is 12v to the solenoid (key on) which the ECU should switch to ground when engine condition is met (don't know specific condition). Return wire to pin 31 has continuity. Connected trouble light to solenoid connector leads and drove around, bulb never lit. Makes me think ECU has not determined switching condition has been met. Or ECU not grounded, but would car run without ground?

Move to code 21: engine coolant temp sensor out of range. Replaced coolant sensor and checked ohm resistance for old and new sensors, seems close to chart someone published previously (see image attached). Engine cooling fan switches on after extended idle. Checked continuity of wire from connector to pin #7. Will check voltages at sensor today. Clearly the ECU recognizes sensor voltage change to switch on coolant fan. Have WBO2 to install to check whether O2 sensor is switching to closed loop, waiting on AEM to replace my faulty display.

Finally code 53: Throttle Position sensor too high . My TPS is 0.865 volts. From what I've read, this is in range, i.e. does not exceed 1.0v. Checked reference voltage is 5v, checked ground lead to battery negative post is 0.00 ohms.

So honestly, I can't see what's at fault, hence why I just swapped in a spare ECU to test. Otherwise car run good, for what it is. Has me scratching my head. Thanks for any help.
 

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No, there are two eight pin. but otherwise the sensors are direct wired into the harness to the ECM. I think if you had a 'connector issue' it would be higher resistance due to corrosion or a open circuit. I've already checked continuity from the sensors/solenoid directly to the 60 pin ecu connector. Maybe I will back probe with key on to check voltages received at the ECU. Thanks
 
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10 pin salt & pepper shakers are for the 5.0's. Seems like you've done some exhaustive testing on the components. In my limited experience, after component testing, the two main areas that are left are the wiring harness and ECU. Granted, you've tried 2 ECU's. Keep in mind they're both 30+ years old and one of the main complaints about them is, as they age the capacitors tend to leak causing all kinds of issues. You seem electrically competent so you may want to try pulling the case off and examining the board for obvious leakage, etc. The ECU Exchange will rebuild it for a reasonable price.

The other area would be the 30+ year old wiring harness. Connectors are brittle, wiring has been tugged on over the years rendering loose connections, harness has probably been modified at some point, etc. I swapped a '93 5.0 harness into my '54 Ford and had nothing but trouble with it. Pulled it out and replaced it with a new Painless unit and it made all the difference in the world. Car has been trouble free.
Just my $.02.
 
evintho, thanks for your 2 cents and compliment: "you seem electrially competent". I'm a retired Ford engineer and I did all sorts or Fox body 2.3L development including early turbos and SVO. Some people can assemble guns blind folded, I could assemble a 2.3, although timing the cam would be tricky, lol. Tomorrow I'll run the AEM WBO2 test. If car switches to closed loop when warm and goes rich at WOT, then I'll just let it slide because it starts and drives well, for a 2.3. I also ported the head, and manifolds, bumped the CR, added a N/A Boport cam and made a 2.25" exhaust. So now it at least revs to 5.5k, not fast but slightly better fun. It's my wife's summer convertible, meant for top down and around town. Not a valuable car, althought clean and rust free.

Maybe someone else with some other experience will chime in with a futher tip. Thanks. Enjoy your '54, it's younger than me.
 
Thanks, everything looks good inside the ECU but I'll check out the ECU Exchange
I've said it a few times in different threads, but my car ran fine, showed codes fine, 'seemingly' nothing wrong with my ECU. I sent it out to ECUExchange just for piece of mind and they found multiple issues with it which they repaired.
 
. That computer is about to collect social security in computer years.....ever notice anybody using a 30 year old fone? Yeah they may still work (can you spell 'analog ') but needs 'updated'
Imagine using a first or even second generation computer :doh:
 
. That computer is about to collect social security in computer years.....ever notice anybody using a 30 year old fone? Yeah they may still work (can you spell 'analog ') but needs 'updated'
Imagine using a first or even second generation computer :doh:

This is period correct for an A9L :D

1744938691556.webp
 
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