Need to find 1995 GMC Sierra 1500 5.7L V8 O2 sensor wire

10

Asked by Nov 12, 2012 at 10:52 PM about the 1995 GMC Sierra 1500 K1500 SL 4WD Standard Cab LB

Question type: Maintenance & Repair

I am doing work on my 1995 GMC Sierra 5.7L V8 I recently purchased. It is idling very rough and stalls
when put into gear. When looking through the engine bay, I discovered that the O2 sensor wire was
cut, and I am trying to find where it was cut from. According to the Haynes manual which I have, the
wire is purple and runs from the ECM, but I cannot find a loose wire cut leading from the ECM.

If someone could perhaps tell me which pin the O2 wire leads from the ECM in this model, it could
help me a lot.

Thanks

11 Answers

850

jeff i don't think the o2 sensor disconnected would make the truck stall sounds like a vacuume leak. check hoses and spray intake with carb cleaner where gaskets are if idel picks up you found your problem.

1 of 1 people found this helpful.
34,655

I agree with Santa. Also try pulling codes from the computer, if that wire is cut and you didn't notice the check engine light on then the light is probably covered or burnt out. Refer to the steps here to get your codes. http://www.ehow.com/ how_7603344_run-chevy-obd1.html while pulling the codes the truck will act quite strange but its nothing to worry about.

1 of 1 people found this helpful.
10

I do believe that the problem is likely a vacuum leak (or low fuel pressure, which others have determined to cause similar problems), but I do wish to find out where to reconnect this O2 sensor to.

1 of 1 people found this helpful.
34,655

Is there a junkyard nearby? There have been a few occasions where I have gone to the local junkyard and used one of their vehicles to reference things like this. If you do this I would advise tracing the wire all the way back to the connector that it hooks to. That way if your wire isn't tucked inside the loom that its supposed to be you still know which wire to splice the new one into. You will be looking for any GMC or Chevy pickup any size from 88-95.

1 of 1 people found this helpful.
40

how many o2 sensors does a 95 gmc sierra have with the 5.7 in it an where are they all located I located the one coming from exhaust manifold to catalytic convertor if can help would be very thankful

4 of 4 people found this helpful.
34,655

Should be only the one unless this is one of those old 1995 General motors cars with the weird compute.

Mine has 2 o2 sensors and its a 1994 gimcrack truck 5.7

34,655

It's a showy but useless truck?

40

for the record it has one o2 sensor and it is on the drive side header next to the steering shaft, it looks like a spark plug and uses the same tool to remove! well almost the same, it is a deep well socket with a gash along the side. But you get the point! your stalling could be a ton of things! Not likely the o2 sensor tho. That would make it run rich! people delete them all the time. Not a good idea for economical purposes. If you just bought the truck the first thing I would do would be to put cleaner in the tank and drive the piss out of it until your fuel light comes on then top off the tank followed by a new fuel filter! Clean your idle air control valve, EGR, and replace your air filter with a Fram, yes I said a FRAM! Do not overlook the EGR, really good youtube videos on your exact truck and engine. Completely details the EGR valve and how it usually just needs a new gasket and cleaning! FYI Nearly everything on your engine works exactly the same as the 305 and is usually the same parts as long as you are not under the valve covers. So include that in your youtube searches! 80% of these trucks were produced with the 305 so they are more common and more tutorials with the 305 as a keyword! Clean the hell out of your TBI, while you are there either rebuild the damn thing or at least put a new gasket under it and look at how the 2 injectors are spraying. If the spray is not perfectly conical in shape then you really should replace the filters inside them if not replace them. Then put it back together and kick your self for not rebuilding it cause it only costs 30 bucks! Mod you fuel pressure reg with an adjustable one. Really easy to do stuff if you know how to use Youtube! Then check you fuel pressure with an inline gauge. If low then replace your fuel pump. FYI this all costs $115-$180 on Amazon.... So get to work! Replace the coolant temp sensor on your center intake head (right in front of the TBI)! If the computer gets a false signal from it, your engine can fall on its face because it is trying to run as cool as possible to prevent overheating! Costs $10 and is the number one reason people give up on their A/C repair. ####WARNING##### do not remove the temp sensor while engine is hot, this goes directly down into your water jacket on the engine!!!! The giant relay in your fuse box under the hood that controls the A/C has a kick out side on it from the computer, this allows the computer to shut down the compressor. I have seen many people beat their heads up against the wall while holding a manifold gauge reading normal parameters over something as simple as that. Sure sign that the temp sensor is malfunctioning!!! Your compressor low pressure switch does not receive voltage when the engine is at operating temps! NOTE# the A/C clutch will engage and the switch will have power when you first start the engine, your computer completely ignores all other sensors until the pre-heater has warmed up the TBI and the engine idles down to normal operating conditions! So put the pre-heater back on!!!! I have had three backyard mechanics give up and bring their car to me in just the last week for this same problem so do not over look it! I love when summer arrives, is an easy 50 bucks!! I have exact same truck 200k purrrrrrz like a kitten! I tap the key and it fires instantly like it is wound up and waiting! Red over Maroon, pristine condition!!! Good luck and stay Chevy!

4 of 4 people found this helpful.

1995chevy , is a 95 the same as a 90 ? I have a 90 gmc Surb 5.7 that starts then dies - I fixed vac hoses and now it is not starting at all - can hear pump

I have a 91 gmc sierra 1500 5.7 tbi when cold rough idle 5 to 10 mins later when warm runs idle good and run good

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