Archive for the 'GMC' Category
Tom’s question:
i have a 1988 GMC pickup 1/2 ton rear wheel drive,305 v8,with an automatic/overdrive transmission believed to be a700R4 trans. i have had it overhauled,and i have attempted an overhaul myself,the trans. seems very strong in low, and 2nd, it even seems to work fine when it has set over night, but when warm it will not shift out of 2nd, any ideas?”
Answer:
Visit a good transmission mechanic when it won’t shift out of second. They can hook up their transmission computer to the vehicle and do a couple simple tests. This could tell you if it’s a mechanical problem, such as a bad automatic clutch, or an electrical problem, like a bad solenoid inside the transmission. You might get lucky and find an electronic problem exists. Your only other option is to pull the tranny off again and pull it apart to see if a mechanical part has failed. Good Luck,
Craig’s question:
My 97 Sonoma failed the emissions test for the code “inefficient catalytic converter.” So I went to a local muffler shop and had an aftermarket converter installed. I was told to drive it a couple days after the computer was reset, and I did. But, it still fails the emissions test with the same cat code. What went wrong?”
Answer:
Well, theoretically it could be any of a number of things, from a bad oxygen sensor to an exhaust leak to an intake leak to any of a number of other possibilities. BUT, from my experience with those GMCs and aftermarket catalytic converters, I’d guess the new cat just isn’t working correctly. I’ve had that happen to me in the past, and I won’t use anything but OEM cats on those GMCs now. Something about how the aftermarket cats are made, they just don’t synch correctly with the vehicle’s fuel injection system and keep tripping the code. The vehicles seem to run perfectly fine with the aftermarket cats, but they won’t let you pass the emissions test because they keep tripping the inefficient cat code. I’d advise trying an original equipment cat and see what happens.
REYNALDO MEDINA’s question:
” CODE P0440 INTERMETENTLY SHOWING UP. I KNOW THAT IS ABOUT THE EVAPORATIVE EMISSION SYSTEM. WHAT WILL BE YOUR SUGGESTION, TO FIND THE CAUSE OF THIS CODE? MY CAR IS 2000 GMC JIMMY 4.3L ENGINE. SMOKE TEST IS SO EXPENSIVE. Any cheaper way in mind? “
Answer:
P0440 is the code for evap malfunction. The possible causes are bad evap hose connections, a leak in the intake system, or a bad evap cannister purge valve. The only way to really check it out is with a smoke machine, but you could try putting two or three pounds pressure into evap hoses and then spraying dishwasher liquid mixed with water on all the connections to see if they bubble up (you can’t use much pressure or you can damage the evap system.) If you can’t find any leaks, the cannister purge valves do go bad quite often on those 4.3 Jimmys. It’s just a guess without checking the whole system out, but if you can’t find anyone willing to smoke check the system at a reasonable cost, a guess may be your next option.
Steve’s question:
“Hi, my ’97 Yukon dash light fuse keeps blowing out. I’m assuming there is a short in the system. What steps should I take to pinpoint my electrical short? Your help is greatly appreciated…Thanks!”
Answer:
Since the dash light fuse keeps blowing, somewhere in that system you have a short. Tracing down shorts is a REAL pain, as they can be anywhere, and taking apart all the dash can be messy. BUT, in my experience with those Yukons, normally such a problem is in the actual dash unit that comes out as one piece. I never personally fix them myself, I remove the dash unit and take them to a local speedometer radio shop that repairs them. They normally charge between 100 and 160 dollars to fix the dashes. They have all the equipment to trace down a short and know exactly what to look for. A new dash is a small fortune, so nobody replaces them new.
REYNALDO MEDINA’s question:
My 2000 GMC Jimmy 2WD 4.3 L IS INTERMETENTLY SHOWING THE CODE P0440 AND P0442 EVERY OTHER WEEK. DO YOU HAVE A TRICK OR OTHER SOLUTION TO REPAIR AND FIND OUT WHERE THE SMALL LEAK IN THE EVAP SYSTEM? BECASUE GOING TO DEALER TO SMOKE TEST THE SYSTEM WAS SO EXPENSIVE. ANY SUGGESTION FROM YOUR EXPERTISE? THANKS IN ADVANCE
Answer:
Well, your leak would be in the evap purge valve, the intake manifold, the hose connections, the hoses themselves, OR the evap cannister. Those are the commonalities of those two codes. So check all the connections and hoses for cracks. If you can’t find any, THE most common problem I see in those Jimmys is a bad evap purge valve if you want to take a good guess at the problem. Now if you want to pinpoint it down, you’re not going to have the equipment and experience to do it yourself (smoke machines cost a grand and upwards.) So in that case, find a good independant mechanic with a smoke machine. They should charge a lot less than the dealer. But, as I said, I do change out a lot of evap purge valves on that model.
Andrew’s question:
I just had a lot of work done on my 98 Savanna, but the check engine light has come back on. The code is P1336, for crankshaf position sensor value not correctly learned. The van runs fine, but I’m leery about taking it back to the mechanic after I’ve already spent a lot of money. What do you suggest?
Answer:
Well, this same scenario actually happenned to me years ago. I suggest you go back to the mechanic for a simple computer relearn procedure, which he’d certainly do for free. On that GMC van, when computer parts are replaced, a relearning process has to be done to set the computer correctly. And for some weird reason, when this process is done by a mechanic, it has to be started with the foot off the brake pedal. But once the test is started, the mechanic must leave his foot on the brake pedal during the entire process. If he forgets and takes his foot off the pedal for even a second, you will be left with that P1336 code stored in the computer. Hey, everyone makes mistakes, especially with modern computer systems, so I’d just let him take care of it.
Dave’s question:
I recently bought a 2004 Gmc Sierra Crew Cab 1500 Z71/5.3l 4×4. Intake manifold gasket went on it. Only 79,000km on it.2 right side O2 sensors went with it. Anyway, $2,000.00 I had 2 pay because they said it wasn’t covered. Later I read my owners manual and it said under the Emmision Control System Warranty- Defects and performance 4 light duty trucks is covered 4 the first 3 years or 60,000km.- It also said defects and performance 4 heavy duty trucks is covered 4 the first five years or 80,000km. Question: My insurance coverage says my truck is H/D . What would b considered the H/D 4 that year? Would mine qualify? Why would it come up as H/D on my insurance? Do u know of all the warranties? I live in Alberta Canada.
Answer:
Yes, heavy duty trucks are not covered by warranties in the United States, I know that. As for Canada, I’m not sure what the law is, but it’s probably the same. When a vehicle is listed as heavy duty commercial, most warranties don’t cover much of anything. I’ve seen guys have to fix things on year old Chrysler trucks that they had to pay for without warranty because of this all the time. You’ll never beat the insurance game boys because they write the rules. I’d just advise you to buy a different brand of truck next time, as those GMCs often have all kinds of problems at a relatively early age. That’s probably the only way you’ll be able to get even,
Question: I just had the power steering pump replaced on my 97 Yukon. The power steering works fine now, but the belt often squeals. My husband sprayed some of that belt quiet spray on the fan belt, and it stopped squealing for a few minutes. Then the racket came right back. What could be making the noise?
GMC Yukon
Answer: Of course, if you haven’t changed the belt and or the belt tensioner, you should do that. BUT, the pulley on those power steering pumps are just press fitted on (they have no bolts holding them on.) And I’ve seen a lot of them not pressed back on far enough when the pump is replaced (you don’t get a new pulley with the new pump, you reuse the old one.) Have the pulley checked to see if it isn’t flush with all the other pulleys in the system. If so, just have it pressed further back on. This can be done on the truck with a special tool that most mechanics have.
Question: My 2001 GMC Yukon groans when I turn the steering wheel to the left. It’s full of fluid, so I changed out the power steering pump. It still makes the same exact noise. What can it be?
gmc-youkon-2001
Answer: Yes, they’ve actually had some problems with the steering box on those Yukons. The valving inside the box goes bad and can groan when turned to either side (normally they will groan only one way or the other, as usually only one side of the box breaks down and the other works fine–so yours may groan to the left but not to the right.) I’d bet a new power steering box would solve your problem.
