Optical Sensor Filter Harness

Discussion in 'GM 6.5 Diesel Engines' started by Bullseye240, Oct 29, 2008.

  1. Bullseye240

    Bullseye240 New Member

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    I recently added one of these "Optical Sensor Filter Harness" to my truck,I say added because I couldn't find one to remove in order to replace it. Since it has been in place the truck has randomly thrown codes 15 and 48. Last night on the way home it would randomly downshift from O/D at 45 mph and currently only has code 15. The first time it threw both codes was right after installng the "filter harness" and O/D wouldn't work. I immediatly figured since I had moved the engine harness around so much I had managed to break some wires or something since both sensors failing at once seemed unlikely to me. I found another engine harness from a donor truck and installed it above the manifold and the problems went away till yesterday (ambient air temps in the mid to low 40's to mid 50's). I understand why it kicks down out of O/D to heat up the engine because the ECM is told that the coolant is cold (makes sense, diesel engine cold add fuel and therefore produce heat). My problem is why has this started since I installed this thing to correct a stumble/stall problem which it still has and I traced to a bum lift pump and will replace this weekend with Turbine Docs prefilter/FRB pump setup. Same donor truck will likely donate its filter housing for a feed the beast mod. I checked the new harness before install and couldnt find anything resembling the "filter" anywhere on it. Is this thing some sort of scam or did 94's not have one and I just wasted some money on it? Love my Blazer:thumbsup: it just test me at times!!!!!:mad2:
     
  2. gmctd

    gmctd Diesels, Anonymous

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    '94-'95-some'96 required the OS Filter due to EMI\RFI electrical noise generated by the new-series alternator - some trucks needed the filter worse than others - some trucks did not need filtration (my engine did not) - quite obviously, if you installed one and the engine runs worse, remove it - no-brainer, there - stalling is usually the FSD\PMD - Heath kit solves that, quite readily - next is the original-series IP: 5521 not sensitive to electrical noise - next is the crimped-only IP harness, known to be failure-prone in the OBD1 and early OBD2-to-'97 trucks - 35bucks from most IP vendors, the improved version has crimped and soldered connections on fine-strand silvered-conductor teflon-insulated wiring - just do it.......................
     
    Last edited: Oct 29, 2008
  3. Bullseye240

    Bullseye240 New Member

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    I have the Heath kit and no probs as I have tested with another new PMD with no change. Who sells the harness?
     
  4. gmctd

    gmctd Diesels, Anonymous

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    Heath, etc...................
     
  5. Bullseye240

    Bullseye240 New Member

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    I've looked on the Heath site and could only find the filter harness any other vendors. I haven't seen it on S&S either.
     
  6. DEERE3594

    DEERE3594 I welcome everyone...not just Penguins!

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    What harness are you looking for?
     
  7. Bullseye240

    Bullseye240 New Member

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    Main engine wiring harness that runs to ECT, IAT, IP, MAP etc...
     
  8. Bullseye240

    Bullseye240 New Member

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    Well gotta head to work so I'll check back with ya later or tomorrow. Thanks in advance.
     
  9. gmctd

    gmctd Diesels, Anonymous

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    Not even - you want the IP harness, which inter-connects the IP and Fuel Solenoid and PMD (with the black ground wire that must remain attached to the top of the IP), thence connected to the main engine harness - gots ta pull the intake manifold off to see and replace it
     
  10. Bullseye240

    Bullseye240 New Member

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    Well I'll be pulling the manifoild this weekend for something else so I'll look into which of the two is in better shape and use it. Will probably replace the coolant sensor since I think it original and has 234000+ on it, besides its only like 12-18 bucks. I went out before work and messed with the connection on that sensor and on the drive to work had no tranny related issues. So its most likely corrosion related and easily fixed. I also know for a fact that 4l80E's dont like low voltage and will drop O/D when it gets below 12 VDC.
     
  11. RadioMan

    RadioMan Recruit

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    Check out Caig Industries (Google is your friend). They have THE stuff to remove corrosion and also stuff to insure that it won't come back.
     

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