'86 LG4 no comm w/ OBDI scanner- TSB for this?
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Car: 1985 Trans Am T-Top
Engine: 305 TPI
Transmission: T-5 5 Speed
Axle/Gears: 3.42 posi 1LE 10 bolt
'86 LG4 no comm w/ OBDI scanner- TSB for this?
Hello,
On my 86 trans am, the SES light comes on as its supposed to at start up, sometimes goes on while driving. The car runs well. I wanted to see what code it was throwing so i used the wire jumper trick first, no result. i then hooked up my Innova OBD1&2 scanner, which has worked perfectly on other obd 1 and 2 cars and is supposedly compatible w/ GM.
The scanner reads "no communication w/ ecu". I tried it with ignition off, on and running.
I saw on a website there was a TSB for this problem on 1986 cars, but couldnt get the details.
Is it a bad connection or a prob with the ECU?
anyone have a link that shows the full TSB?
thanks
On my 86 trans am, the SES light comes on as its supposed to at start up, sometimes goes on while driving. The car runs well. I wanted to see what code it was throwing so i used the wire jumper trick first, no result. i then hooked up my Innova OBD1&2 scanner, which has worked perfectly on other obd 1 and 2 cars and is supposedly compatible w/ GM.
The scanner reads "no communication w/ ecu". I tried it with ignition off, on and running.
I saw on a website there was a TSB for this problem on 1986 cars, but couldnt get the details.
Is it a bad connection or a prob with the ECU?
anyone have a link that shows the full TSB?
thanks
#2
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Car: 1985 Trans Am T-Top
Engine: 305 TPI
Transmission: T-5 5 Speed
Axle/Gears: 3.42 posi 1LE 10 bolt
Re: '86 LG4 no comm w/ OBDI scanner- TSB for this?
ok, the TSB was for a '96 not '86
can i test the ALDL port for ground or voltage?
can i test the ALDL port for ground or voltage?
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Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: '86 LG4 no comm w/ OBDI scanner- TSB for this?
I believe you need a 4K resistor on the std cable to connect to the CCC systems.
Can't get to the diagram from where I'm at or I'd link you to it.
Do a quick search for the std cable diagram. It shows the resistor that is used for carb applications.
HTH
Can't get to the diagram from where I'm at or I'd link you to it.
Do a quick search for the std cable diagram. It shows the resistor that is used for carb applications.
HTH
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Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: '86 LG4 no comm w/ OBDI scanner- TSB for this?
You'll have to talk to Innova on the 4K resistor issue. My Autoxray works fine on my '84, '85 and '87 carbed ECMs. Got the scanner configured for the right year/Vin? Correct cable?
Easy enough to test continuity to ground for the ALDL ground pin with a test light or meter.
Easy enough to test continuity to ground for the ALDL ground pin with a test light or meter.
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Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: '86 LG4 no comm w/ OBDI scanner- TSB for this?
OK, it was 1.5 K resistor but was called R4.
See here and test if your cable has it.
http://winaldl.joby.se/aldlcable.htm
See here and test if your cable has it.
http://winaldl.joby.se/aldlcable.htm
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Car: 1985 Trans Am T-Top
Engine: 305 TPI
Transmission: T-5 5 Speed
Axle/Gears: 3.42 posi 1LE 10 bolt
Re: '86 LG4 no comm w/ OBDI scanner- TSB for this?
Im pretty sure the prob is with the ALDL. I should get some voltage readings from other pins too, correct? Im pretty sure its the connection since the jumper wire trick didnt work either. I mostly started this thread because i thought there was a TSB for this prob.
Naf-does your autox-ray work on the efi cars of the same years w/ the same adapter as the carb?
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Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: '86 LG4 no comm w/ OBDI scanner- TSB for this?
Yeah. My autoxray has worked on a couple TPI and TBI cars that I've connected to, as well as later model stuff. Hasn't failed me yet. If the paper clip trick didn't work it's likely your ALDL. I've heard that the connector is prone to lose its ground but have no personal experience of this ever happening.
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DURTYBIRD
Tech / General Engine
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06-08-2004 08:01 AM
86, autoxray, camaro, codes, communication, compatible, ecu, hacking, lg4, obd1, obdi, scanner, trans, transmission, voltages