What voltage at ECT connector?

#21

For clarification, I plug the ECT sensor in, I disconect the eec connector and then check resistance between the ECT pin7 and the SIGRTN pin 46? Should be less than 10k ohms?
 
#23
Originally Posted by joel5.0
Looks like you have a short in the wiring harness.
Im not sure I understand what I need to do here.
Disconnect ECT connector (got that) and ECM's (eec connector?) and check resistance from ECT terminal (Pin 7 on eec connector?) to SIGRTN in the ECT connector (I understand that) (previous is first test?) + from ECT terminal (pin 7 again?) to a good ground nice (This is second test?). LUK
Do I have this right?

First test I got 97.1 K ohms
second test I got 97.2 K ohms
 
#26
"shorts" don't present 92k ohms of resistance, but it could represent a "parallel" path that would result in a resistance seen at the EEC less than half of the lowest resistance value in parallel. I suspect the sensor was still plugged in but he'll have to verify.
 
#27
Looks like that ECM is also defective. Last test to confirm.

1. Leave ECT, ACT, ECM disconnected.

2. Check resistance at ECM connector between:
  • Pin 7 & 25 and pin 40
  • Pin 7 & 25 and pin 60
  • Pin 7 & 25 and pin 20
  • Pin 7 & 25 and pin 49
They all should be >10kΩ

3. If the above steps are OK, disconnect ECT, leave disconnected, run a KOEO and check if code 51 shows up.

4. If it doesn't, remove pin 7 from ECM connector, reconnect ECM and rerun a KOEO...... if code 51 doesn't show....... ECM is fubar.
 
#28
tmoss said:
sounds too high - what was the temp of the engine? Now measure the resitance of the sensor itself to see if it is anywhere close to 97k ohms
Click to expand...

Resistance across the unplugged ECT sensor is 80.9 K Ohms.

It warmed up a bit here, its almost 40 degrees in the garage.
Engine hasnt been started for a few days, its at ambient temperature. 40F

All the resistance tests above (Including the 97K ohms)was with the ECT and ACT and the ECM(eec) unplugged.
Neg Battery cable unplugged.
I used the unplugged Neg Batt cable for ground.

I did the below tests on both computers, while they were disconnected and out of the car.

Pin 7 & 25 and pin 40 19.2 k ohms
Pin 7 & 25 and pin 60 19.2 k ohms
Pin 7 & 25 and pin 20 open
Pin 7 & 25 and pin 49 83.5 K ohms

I dont understand these results, is something burned out inside the Computer?

3. If the above steps are OK, disconnect ECT, leave disconnected, run a KOEO and check if code 51 shows up.
Click to expand...

I left both the ECT and The ACT unplugged and ran KOEO
Got a code 21 and 24
Did not get a 51 or 54
I assume a code 51 is set by the computer seeing 5 volts at pin 7 on the ecu?
I will take the eec connector apart tomorrow and pull the ECT wire out and run the test again.
 
#29
I took the connctor apart and removed the ECT pin
Put it back together and now It tested at 4.71 volts. WTF
The ACT pin still registered 3.98 volts.
I removed ACT pin and It also tested at 4.71 volts WTFx2
This entire time, I have had the SNEEC IV datalogger hooked up, so I decided to remove it and hook the computer up without it.
Now I have 4.71 volts at the ECT sensor.
I ran the KOEO test and get the code 51 and 54
Great I think, Maybe the SNEEC was the problem.
I try to start the car cold, after it fires it stalls, just like before.
4.71 volts isnt any better than 3.98

I will try to run the previous tests without the SNEEC in place.
 
#31

A little tip for future TS events and aftermarket components are installed, disconnect them and test the system in its OEM configuration (MSD ignition boxes, tuning chips, aftermarket tuners, and SNEEC IV datalogger)

The fact that now you have the correct ECT and ACT (did you check it w/out the SNEEC?) is not necessarily ECT voltage related, reconnect ECT sensor, verify wire signal voltage, clear ECM as tmoss suggested, rerun KOEO and confirm KAM is clear ..... and see how it does. LUK
 
#32

Is 4.71 volts correct for the ECT voltage with the connector off? Shouldnt it be 5.1 volts, the same as Im getting from vref. I still feel this is the source of the stalling problem.


The car still stalls when the sneec is out of the equation. The sneec wasnt causing the stalling.
The ECT circuit is giving the computer the wrong reading somehow.
The fact that it started up and idled fine when the correct voltage was at pin 7 tells me this.

I will try to rerun those other tests tomorrow without the sneec.
 
#33
4.71 vdc is above the 4.6 vdc maximum threshold for the ECT or ACT circuits. IOW.... the system is within its working range as far as the ECM is concerned. Also keep in mind that when you start the engine with a hard failure code present (ECT is one), the system will switch to Failure Mode Effects Management (FMEM) strategy.... affecting idle, A/F, spark advance, etc.



Now.... look at the following statement.......


Isn't the coolant temperature supposed to raise when engine has been idling for 5 minutes?...... regardless of the ambient temperature? The circuit is within specifications. The fact that you have a code 51 showing with ECT disconnected + if you install a jumper wire at the ECT connector pins, run a KOEO, and have code 61 getting logged....... it's the proof the ECT circuit is within its acceptable working window, the ECM logic will do the appropriate scaling to the correct temperature. IOW.... the culprit or cause(s) for the stalling symptom is(are) elsewhere. LUK
 
#34
Interesting, so it was the fact that the ECT was unplugged, and it went into failure mode, that caused it not to stall.
I see, so I guess Im back to square one?

But the time it started up and didnt stall, it wasnt throwing a code 51. Im not positive, but I dont think it was throwing any codes.
I will see If I can reproduce those conditions.
If it was running in Failure mode, would the Check Engine light be on? Is there another way to tell. It should at least store a code I assume.
 
#35
I was wrong, the SNEEC is definatly what was causing it to stall on a cold start. The time it stalled without the SNEEC, I had left the ECT connector unplugged.
I messed around with it figured out the different things that made it run right and what made it stall and this is my observations.
Voltage is at pin 7 on the EEC, backprobed with a paperclip. Cold is around 29 degrees ambient temperature.
(A laser thermometer would be a big help here to accuratly get the temp of the engine around the sensor, but I dont have one. So I used the thermometer hanging on the wall in the garage)
With the ECT unplugged, The car will stall when cold. 4.71 volts
With my SNEEC IV datalogger plugged in, the car will stall when cold. 2.83 volts
With the SNEEC IV plugged in and the ECT sensor disconnected car does not stall when cold 3.98 volts
With the SNEEC IV removed, and the ECT connected, car does not stall when cold. 3.95 volts.
The common factor appears to be the voltage at pin 7
If I were trying to diagnose a stalling when cold problem again, I would figure the engine temp as accuratly as possible, then I would take a voltage reading at pin 7 on the EEC and compare it to this chart.

Ford Fuel Injection Engine Coolant Temperature Sensor (ECT)

Going into failure mode wont get the engine not to stall, only seeing the propper voltage at pin 7 will do that

Thanks for your help guys. Evan though I was chasing my own tail, I learned alot and hopefully all this info will help someone else..

On to my other problems I guess.
 
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