I tested the resistance from end to end it showed .3 ohms meanings the wire is good.

IM going to try to post the video of the KOEO codes, i think im getting codes 15-12-51 can someone confirm this.

thanks,

chaz

P7150244.flv - Video - Photobucket - Video and Image Hosting

 

15, 12 and I can't figure out that last one. You may have 4 codes total.

 

OK, good feedback. So now we believe the signal return wires resistance is ok, the ECT sensors resistance is within spec & at KOEO, the 5 vdc reference voltage measures 4.7 vdc, "unloaded" (with the ECT disconnected), but with the ECT conncted, the signal return voltage that should be about 2.62 vdc at 86 deg F, is WAY low at .167 vdc.

So, with the ECT's connector in place, on the ECT sensor, probe the 5 vdc reference voltage wire at KOEO & post what the reference voltage measures at the ECT, with it connected & at the computer end of the wiring harness, with the ECT connected.

 

small update, i went ahead and double checked the new thermostat that was 1 month old. IT was failing in the open position. I have replaced it and the operating temp is a bit higher but still doesnt look as high as it should be. IS there a detailed schematic of how the housing / gasket / thermostat all sit on the engine? Im thinking that its not sealing 100% inside the housing and allowing fluid to bypass the thermostat. No external leaks.

 

KOEO radiator fluid at ~132F I back probed the ECT wires while it was connected. THE ECT side gave me a 0.3 Volts, and the sig rtn side 1.7V.

Does this mean i should go ahead and replace the ECT again?

 

Well the Ford ECT table parameters I posted, says the 1.7 signal return volts you meaured, indicates that the engine coolant temp sensor thinks the engine coolant is at about 122F (1.72 volts), so thats real close to the 132F coolant temp you posted.

Now what does the signal return voltage at the computers connector measure????

EDIT: After thinking some about the above numbers you posted, I wonder if you have a nomenclature problem here????

Did you mean with the ECT connected, the "SIG" voltage at the ECT is now reduced from 4.7, to 1.7 & the "SIG Return" to the computer is .167????

 

nomenclature is correct, i think the 4.7 was when it was disconnected. Although im not sure.

i will probe the return line at the computer with KOEO and see what kind of volts i get. I will also reprobe at the ECT as well.

Thanks

 

OK, with the ECT connected re-probe the "Signal" voltage at the ECT sensor & the "Signal Return" voltage AT the computer.

 

OKay KOEO radiator fluid ~ 115 F.

AT ECT / (sig rtn .37 V)
AT ECT / (ECT 2.13 V )

At computer (sig rtn .30 V )

these were taken by back probing, nothing was disconnected during these test.

Whats this mean? is 0.07 volts enough to fool computer? Is this new ECT sensor bad? Do i need a new computer?

what do you think?

 

Well seeing as how the ECT resistance checks out ok, the Reference Signal & Signal Return wires resistance checks out ok, but the 5.0 Ref voltage reads low with the ECT connected & thus causing the Signal Return voltage to the computer to be low, so the error code the computer has set is valid.

The cause of the low ref voltage under load from an in spec ECT, seems to suggest to me that there is a internal problem with the computers 5.0 ref voltage source to the ECT.

Maybe a high resistance connection in a crcuit board solder joint, corrosion in a connector, or a bad component in the computer.

I suppose you could pull the computer, open it up & trace the sig return leads internal connection at the computers conector & maybe try to trace the crcuit board & see if you can find any loose, or suspect solder connections, or bad places in/on the circuit board.

Or maybe try & find another computer to try.

I know re-man computers are available, but I don't know how far back in years.
Yours would likely be worth a core charge, so don't toss it, if you can't find an internal problem.

Let us know what you find.

EDIT: I suppose there is one other thing to do, that'll double check the wires resistance check you did & that is, with the ECT connected, probe the 5.0 Signal lead AT the computer, to make sure it's voltage is low AT the computers connector.

If it measures low, then it'll strongly suggest an internal computer problem.

If it reads ok, then it would suggest a lead resistance problem between the computer probe point & ECT probe point.

 

any ideas on where to get a computer for my ride? Is there anything to be aware of before buying one?

thanks

 

Does this mean, with the ECT connected, you've probed the 5 volt reference at the computers connector & it was low (2.13 volts) or so, like it read when probed at the ECT????

I'll bet most autoparts stores have reman computers. Look for a good warranty.

 

NO i have not traced that wire from the ect to the comptuer yet...guess i will try to do that tonight before buying a new computer. Im just guessing with this not working correctly and getting the code for pcm rom lost thats its the computer. I will try to trace that wire tonight and double check the volts at computer and ect.

 

I tested the ECT wire which was green with a red stripe at ECT and at computer with KOEO The volts were 1.38, didnt bother checking temperature of coolant but if i had to guess it was somewhere around 110 - 135 F. Does this also imply that the ECU is shot?

 

Sure doesn't measure up to anywhere near 5.0 VDC with the ECT load does it.
Sounds like something in the computers 5.0 volt reference circuit is laying down on the job.

So I suppose it's time to open the computer up & have a look see inside, maybe it's something simple & obvious that you can remedy with a clean up, or resolder.

Or if you don't want to fool with it anymore, spend the time looking for a replacement.

Maybe you could get lucky at a slavage yard, but then it's pot luck, no warranty expressed or implided!!!!

Way to hang in there on your trouble shoot & see it through to the end.

Any idea how the computer has come to be zapped????
Just before this problem began, did you get a jump start, or unhook the battery with the engine running, or maybe put a battery charger on, without first disconnecting the B- lead, or hook up/plug in some other kind of electrical/electronic equiptment, or did it just come about by happenstance????

Might be useful to know how it came about.

Anyway let us know how it all turns out.