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Setting timing on 91 V2500 Burb...............what color wire to unplug?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BurbinOR, Jun 6, 2003.

  1. BurbinOR

    BurbinOR 3/4 ton status

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    Thirdgen has the F Body Camaro's wire as tan with black stripe..........no such color animal on my Burb.

    Anyone know which wire to unplug to set the base timing? Location?

    Thanks............ /forums/images/graemlins/laugh.gif
     
  2. ken

    ken 1/2 ton status

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    My '90 Suburban and '88 dually both have the tan (light brown) wire with black strip. That is the one I unplug to time. Also, if the emissions sticker is still ont he radiator core support, it will tell you what color the wire is and what to set your timing at. Good luck.
     
  3. BurbinOR

    BurbinOR 3/4 ton status

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    Thanks Ken. Where is your's located/come out of/standalone??? /forums/images/graemlins/confused.gif
     
  4. ken

    ken 1/2 ton status

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    Right near the master cylinder, behind and over it...it's a lone wire that breaks out of the wiring conduit.
     
  5. K5 NUTT

    K5 NUTT 1/2 ton status

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    Unplugging it usually throws a code 42 frank....but when you unplug it check and ensure timing is at 0 degree's...to clear code unplug battery power..course you should be aware of that after your 79....btw...the chalet came to life today with TBI today....hehehe.

    DW
     
  6. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    [ QUOTE ]
    Unplugging it usually throws a code 42 frank....but when you unplug it check and ensure timing is at 0 degree's...to clear code unplug battery power..course you should be aware of that after your 79....btw...the chalet came to life today with TBI today....hehehe.

    DW

    [/ QUOTE ]

    Cool! so when you goingto help me get the FI on the 75?

    My 88 R20 burb is 4deg but it's also a 454 not a 350.
     
  7. BurbinOR

    BurbinOR 3/4 ton status

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    Ken, Doug - thanks a ton - wire was right by MC, checked it, was 2* retarded, changed it, all is well...........one strange thing is the SES light went away on it's own (no battery unhooked) after a couple of minutes and my scanner didn't detect any codes. /forums/images/graemlins/confused.gif

    'Auto-resetting-computer'?

    Anyway, the distributor hold down bolt hadn't been loose in ages..........setting the timing took longer than the entire tune up did yesterday morning!

    /forums/images/graemlins/thumb.gif
     
  8. FL84K5

    FL84K5 1/2 ton status

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    skinny tires is your cure.
     
  9. BurbinOR

    BurbinOR 3/4 ton status

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    Huh? /forums/images/graemlins/confused.gif
     
  10. K5 NUTT

    K5 NUTT 1/2 ton status

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    Grimy...still not done but at least it moves under its own power. Gotta save coin to buy a vss for the burb...and another vss from howell for project chalet...i think since the emission side of the harness requires a operational vss and must see P-N-RDL to operate correctly...plus i need to cobble up the kickdown cable to worky...did the harness myself this time...no codes on the scanner and everything looks good... /forums/images/graemlins/thinking.gif
     
  11. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    [ QUOTE ]
    Grimy...still not done but at least it moves under its own power. Gotta save coin to buy a vss for the burb...and another vss from howell for project chalet...i think since the emission side of the harness requires a operational vss and must see P-N-RDL to operate correctly...plus i need to cobble up the kickdown cable to worky...did the harness myself this time...no codes on the scanner and everything looks good... /forums/images/graemlins/thinking.gif

    [/ QUOTE ]

    I have a complete 89 454 FI system that is supose to ship monday. Only thing I don't know if I am getting is the VSS. My factory manual says "the VSS is behind the speedometer". I don't know if it's a seperate modual (That's my hope) or if it's part of the cluster and can't be seperated. I'm waiting to hear about it if he was able to remove it. I have to get over to Keiths and get the 350 ECM and harness I traded him some parts for. I'll pop the cluster and see if the VSS is sperate if I get a chance. Let you know what I find if I can get over there this week. I might see about pulling the compete electrical harness off that truck Keith has and dump the glass fuse box in the 75. Basicly update the 75 electrical to 88. Just need to see if Keith is willing to part with that or what he has planned.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    VSS setup (buffer) is bolted to the back of the speedo head for mechanical speedo setups.

    Can't comment on whether they are ALL interchangeable, but my '88 TPI is 2 pulse, as are all the '81+ GM vehicles with VSS, until they went 4(?) pulse. So in other words, if '89 was still 2 pulse, you can use the VSS from any GM vehicle previous, as far as I've seen. One slight difference having to do with the wiring connectors on the VSS, but the wiring connectors on the harness determine which VSS you need.

    VSS will assist/control cruise and lockup (if 700R4/4L60) on your setup as well, that "module" is the one above the gas pedal, if it happens to come with. Everything else VSS is ECM related, and is for *driveability*, not emissions.
     
  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    Well sounds like I got the right parts. 88 and 89 should be near identical. 91 is when they went to the 4L80 and 4L60 and I bet thats when the VSS changed.
    The FI I bought came out of a 89 454 Burb with the TH400. I think this will be a good set up because it's not looking for a lock up converter or to shift any gears etc. 670cfm Throttle body to boot /forums/images/graemlins/smile.gif

    Now the trick will be to hang this VSS onto a 75 cluster LOL.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    I've thought about the older speedometer issues.

    The "easy" fix is to get the '81+ cluster, and replace yours. A more difficult option would be finding a 0-85MPH speedometer in your style (not sure if they were ever made) and taking the '81+ style speedometer, and swapping the "head unit" to the old gauge face. But I don't recall ever seeing a speedometer that was 0-85 except on the '81 or so body style. Pretty sure '80 also had the "new style" speedometer script, but you'd need something like '79 or '78 and earlier.

    Speedometer shops can recalibrate the head unit to the gauge face if you change them. Last I checked it was around $50.
     
  15. K5 NUTT

    K5 NUTT 1/2 ton status

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    90 was when the vss setup changed...no longer bolted to the back of the IC...vss xfer mounted...sent to the drac module under the radio...drac buffered generated a/c signal to be able to account for diff tire sizes...then sent the signal out to a cc mod...ecm...abs ecu..speedo..

    DW
     
  16. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    [ QUOTE ]
    I've thought about the older speedometer issues.

    The "easy" fix is to get the '81+ cluster, and replace yours. A more difficult option would be finding a 0-85MPH speedometer in your style (not sure if they were ever made) and taking the '81+ style speedometer, and swapping the "head unit" to the old gauge face. But I don't recall ever seeing a speedometer that was 0-85 except on the '81 or so body style. Pretty sure '80 also had the "new style" speedometer script, but you'd need something like '79 or '78 and earlier.

    Speedometer shops can recalibrate the head unit to the gauge face if you change them. Last I checked it was around $50.

    [/ QUOTE ]

    Uhhhggg swapping the cluster might be a electrical nightmare. My 75 pre dates blade fuses etc. My oil pressure gage is also mechanical (factory) and my truck has a amp meter not a volt meter.

    Hmmmmmmm Geeee this might just give me the justification to go to VDO gages........Ohhhhh honny how much money do we have in the bank? LOL
     
  17. HarryH3

    HarryH3 1 ton status Author

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    Grim, on rigs with the VSS attached to the speedo, there's a reflective rotating surface inside the speedo that reflects light from the emitter of the module to the detector part of the module. By counting the number of pulses within a given timeframe, the ECM knows how fast the vehicle is travelling. I doubt that your '75 speedo has the reflector inside. /forums/images/graemlins/frown.gif

    But another option is the Howell VSS that Doug mentioned. It screws onto your t-case, where the speedo is connected now, then the speedo cable screws into the VSS. Howell will just need to know that you're using the '89 454 computer to set you up with the correct part. I think they run about $75. /forums/images/graemlins/cool.gif I'm pretty sure that the output from the VSS still needs to go into some type of VSS buffer that converts the variable voltage sine wave output from the VSS into a digital signal that then feeds into the ECM.
     
  18. K5 NUTT

    K5 NUTT 1/2 ton status

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    Re: Setting timing on 91 V2500 Burb...............what color wire to unplug

    Actually Howell sells a 2 pulse vss (tbi) or a 4 pulse vss (TPI)...thats the whole diff there....and of course $75 bux...but to me its the way to go...

    DW
     

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