OBDII or NOT!
Thread Starter
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Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
OBDII or NOT!
Long post so be patient…Wells here we go for the guys that are up on their PCM ‘s and OBDII
I decided to do routine maintenance on the 97 explorer 4.0L OHV today, scanned with a hand scanner and found one code (P0133 - HO2S Sensor, Circuit Slow Response)seems like the MIL has died. <O
So no problem, out comes the laptop and connect to the OBDII, run diagnostics and find that no O2 is registering, although the test shows as READY. Not to be out done I switch to my Palm device and get the same results, all O2’s zero Volts.
I pull all the O2’s and bench test, # 1 bank 2 is a little lazy but passes, the others test OK
Reinstall, bring up to temp, and test at the terminal block of the PCM with a digital VOM, all test as on the bench
Retest with both Palm and Laptop at the ODB connector, but show 0vdc and full trim. <O
I switch to the ford specific test program on the laptop and run a diagnostic on the O2’s and lo and behold I see the fronts switching and the Back almost stationary, <O
The truck is running well with no driveability problems.</O
So here comes the Question…..What is going on?? Any ideas?<O
I decided to do routine maintenance on the 97 explorer 4.0L OHV today, scanned with a hand scanner and found one code (P0133 - HO2S Sensor, Circuit Slow Response)seems like the MIL has died. <O
So no problem, out comes the laptop and connect to the OBDII, run diagnostics and find that no O2 is registering, although the test shows as READY. Not to be out done I switch to my Palm device and get the same results, all O2’s zero Volts.
I pull all the O2’s and bench test, # 1 bank 2 is a little lazy but passes, the others test OK
Reinstall, bring up to temp, and test at the terminal block of the PCM with a digital VOM, all test as on the bench
Retest with both Palm and Laptop at the ODB connector, but show 0vdc and full trim. <O
I switch to the ford specific test program on the laptop and run a diagnostic on the O2’s and lo and behold I see the fronts switching and the Back almost stationary, <O
The truck is running well with no driveability problems.</O
So here comes the Question…..What is going on?? Any ideas?<O
Moderator
Joined: Jan 2001
Posts: 56,979
Likes: 2,734
From: Virginia
Was the P0133 a memory code or a hard fault. If it was a memory code, that may be why the MIL light is not on.
I would take the battery cable off for a few minutes and then try your tests again.
I would take the battery cable off for a few minutes and then try your tests again.
Thread Starter
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Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
the P0133 was a hard code, MIL burned out. Pulled PCM, PCM clean and dry, grounds good, Reset codes, but same situation.
Rebuilt Alternator, brushes down to 3/16th, charging @14.34vdc
This vehicle is used for V Fire Rescue (dive unit)
Rebuilt Alternator, brushes down to 3/16th, charging @14.34vdc
This vehicle is used for V Fire Rescue (dive unit)
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
I switch to the ford specific test program on the laptop and run a diagnostic on the O2’s and lo and behold I see the fronts switching and the Back almost stationary,
The only time you'd normally see the downstream sensors switch is if the cat is dead or during the catalyst efficiency test.
Steve
Thread Starter
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Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
thanks projectSH089.
I know that we are in the groove, but I was looking for some insight of why it does not regiser in the generic OBD test screen, shows 0vdc for all O2's. Could the PCM be withholding this info even though it passes on all the other info..
I know that we are in the groove, but I was looking for some insight of why it does not regiser in the generic OBD test screen, shows 0vdc for all O2's. Could the PCM be withholding this info even though it passes on all the other info..
