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Old 09-26-2011, 04:36 PM   #1
Urban Suburban
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Question 6.2 service engine soon - no codes????

Like the title says... my service engine soon light has been coming on and going out for a week or so. It cam on for the first time just before i lost the rear brakes. I figured they were related. brakes have been fixed and the truck scanned... No codes came up. The light came on a few times over the weekend. The last time I tapped the dash to be a smart ass and the light went out. I guess I need to make sure it didn't burn out or something. anyone have any thoughts. I was told that the 6.2 Diesels don't really use much of the computer... is this true?
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Old 09-27-2011, 02:46 PM   #2
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Re: 6.2 service engine soon - no codes????

Yes,6.2s don't use the computer. Maybe the light is acting up or something with the hydro-boost?
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Old 09-27-2011, 04:59 PM   #3
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Re: 6.2 service engine soon - no codes????

Interesting... Any idea how the hydraboost fits in?
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Old 09-30-2011, 02:32 PM   #4
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Re: 6.2 service engine soon - no codes????

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Originally Posted by Urban Suburban View Post
Interesting... Any idea how the hydraboost fits in?
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It doesn't.
The computer doesn't do much on the diesel applications. The TCC engagement is about the only useful function. Glow Inhibit, and HPCA can be run with relays and a temp sensor. EGR can be run on vacuum controls.

According to the 1989 R/V schematics
The LH6 Diesel ECM Outputs;
  1. EGR
  2. HPCA Housing Pressure Cold Advance
  3. Glow Plug Inhibit
  4. TCC Torque Convertor Clutch
The LH6 Diesel ECM Inputs;
  1. MAP sensor
  2. ESS Engine Speed Sensor [on top of the vacuum pump]
  3. VSS Vehicle Speed Sensor
  4. Brake pedal engagement switch
  5. TPS Throttle Position Sensor
  6. Coolant Temp Switch
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Old 09-30-2011, 02:36 PM   #5
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Re: 6.2 service engine soon - no codes????

interesting... we have scanned it an no codes with two different mechanics and computers???? will have to see whats the deal. I did notice that it looks like there is some glue where someone tried hiding it with tape at some point
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Old 09-30-2011, 05:04 PM   #6
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Re: 6.2 service engine soon - no codes????

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Originally Posted by Urban Suburban View Post
interesting... we have scanned it an no codes with two different mechanics and computers???? will have to see whats the deal. I did notice that it looks like there is some glue where someone tried hiding it with tape at some point
Read the codes the old fashioned way. http://www.obd-codes.com/faq/read-gm...codes-free.php
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Old 10-06-2011, 01:29 PM   #7
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Re: 6.2 service engine soon - no codes????

so i had a broken glow plug and two broken glow plug connectors. The bulb is defiantly burnt out now but still smokes a lot and runs ruff on a cold start
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Old 10-06-2011, 07:30 PM   #8
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Re: 6.2 service engine soon - no codes????

the service engine soon really only looks for shorts
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