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Thread: 3.4 Troubleshooting

  1. #1
    Join Date
    Aug 2008
    Buffalo, N.Y.
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    Default 3.4 Troubleshooting

    Is your SES light on in your 3.4 and your sick of not knowing what it is? Been to an auto store to have your codes read only to find out they can't do it? Or maybe you tried the "paper clip" method of flashing code only to realize that too was in vain?

    The 3.4 PCM is a hard nut to crack. It's technically a mix between OBD-I and OBD-II which GM switched to in the 1996 year. This "OBD-1.5" uses the same trouble codes as OBD-I but is a flash only system, unlike that of the OBD-I "chip" computers. Many scanners don't work on our 3.4's, often times leaving us in the dark or forcing us to pay 100$ to a mechanic just to find out that our 20$ oxygen sensor is bad. Instead of paying a mechanic that kind of money, i would suggest instead buying a scanner which will read your code and give you plenty of other diagnostic information to boot. The Actron 9150 scanner is generally found on ebay for 150$ and would be a worthwhile pick up. This scanner will read the codes to your 3.4 as well as many other vehicles and also let you stream live data. For you 95 3.4 guys this is especially important since your cars came with the OBD-1.5 PCM, but an OBD-II diagnostic port. The Actron 9150 kit comes with the attachment you will need to read codes. There may be many other scanners out there but this one has certainly got it all.

    Actron Scanner

    For those of you who have a means of getting your codes read by a friend or a mechanic but don't know what those trouble codes are, you can either pick up a haynes manual which will list and briefly describe those codes or you can just take a look at these GM OBD-I Trouble Codes

    Haynes Manual

    Unfortunately, OBD-I trouble codes are still rather ambiguous and difficult to understand. They do not always pinpoint the exact issue but often help to find the issue much faster.

    Troubleshooting your 3.4 PCM is not as hard as it would appear to be. As long as you have a proper scanner and list of trouble codes you can make your life much easier with these cars.
    Last edited by tkoforpresident; 06-27-2009 at 11:59 PM.

    93 3.4 Firebird
    Pacesetter Headers, Flowmaster 80, Comp 1.6 RR, Custom Cam, Cloyes 2x Set, P&P Heads & Intakes, Ram Air Intake, Posi Rear w/3.42's and Disk Brakes, OBD-1 Swap.
    Cam and Heads by Tune By

  2. #2
    Join Date
    Aug 2011
    Rep Power

    Thumbs up WTH

    [FONT="Century Gothic"][SIZE="4"]I cant tell you how many web pages and assorted crap ive read my 94 has been a great car till about a couple of weeks ago the ses light started coming on and i figured its been like a year since i did a tune up replaced the plugs and wires ran great for a couple of days then started stalling and i changed the fuel filter now it barely runs i checked the sensors and found the TPS reads 5 volt at idle and 4.25 at WOT that dont sound like allot but ill change that on mon. the main concern is im only putting out 13 and 3/4 volts .tried other scanners to no avail. thanks youve helped a bunch awesome site]

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