Archive for the 'Chevrolet' Category

2004 Chevy Tahoe’s AC compressor won’t come on and stay on

Nat’s question:

” My 2004 Tahoe’s AC compressor blew last week. So I installed a new compressor and drier and orifice tube. But the AC won’t come on and stay on. Help me!”


Well, you might get a really quick and easy fix here. Those AC systems are all computerised these days, and as many computers are, they need resetting when a problem arises. Simply disconnect your battery for five minutes. Then connect the terminals back on and start up the engine. I’ll bet it starts working then. That happenned to me once and nearly drove me to the looney bin until I figured it out.

1999 Chevrolet Prizm MIL light on all the time

Peter’s question:

” Hi , I drive a 1999 Chevrolet Prizm. It has MIL on all the time. There is a code: PO420. Where is the problem? I am seeking your advice. Thank you. Regards, Peter”


OK, PO420 is the code for catalytic converter low efficiency. There are three possible causes: a bad catalytic converter, bad wiring, or bad oxygen sensors. THE most common problem is a weak catalytic converter, but pinpointing if this is your problem is rather hard. The oxygen sensors give feedback to the main computer about how the cat itself is working, and PO420 sets if the computer decides the cat is bad using this information. This is a very complex algorism in the computer software, and checking can be done by a professional mechanic indirectly using an oscilliscope. Since this costs a ton, and isn’t always completely accurate, you might just try replacing the rear oxygen sensor (the one after the cat.) It is the cheapest part in the system and a bad rear sensor can trip that code. Now if that doesn’t do it, a new aftermarket cat could be welded on your Prism, which would save you hundreds over the cost of an OEM cat. But it’s still going to cost you two to three hundred dollars for that guess. So I’d try the rear oxygen sensor first if you want to take a stab at it. BUT, on the plus side, an inefficient cat code really isn’t going to make your Prism run any different. It will just make your car fail the yearly state inspection if your area does emissions testing.

1974 CORVETTE rear suspension problem

Ralph’s question:



Realize that Corvettes are rich men’s toys. You have some serious problem in your rear drive axle and suspension, as that is a rear wheel drive machine. Even though it’s rather old, that Corvette has a pretty fancy independant suspension and drive train back there. Something is either bent or broken. ANY good front end shop could at least show you what has gone wrong, and you could get estimates at different places to see what it could cost to repair. Hopefully you can find a guy who’ll fix it for a fair price. As you have found out, I’d stay away from Corvette specialists as they are rather like Doctors in their pricing structure. If you want to look around a little and make some calls, I’ve always had good luck with heavy suspension work like that using garages that do nothing but suspension work, often specializing in heavy duty trucks. And if no truck places around you do such work on Corvettes,they will certainly know of a place that does. Talk to a few real mechanics and someone can certainly help you out. If you happen to be in the Houston area, simply call Mr Cotton or Cotton Brothers Front End on 500 Fairview and he could certainly get it fixed for you. I’ve been using them for over three decades now.

Chevrolet S-10 Blaze Stalling All the time

Henry’s question:

“I’ve got a 97 S 10 Blazer which is dying on me all the time. I took it to be scanned, but there were no trouble codes. What should I try next?”


Well, theoretically there could be LOTS of things wrong. But since there are no codes, I’d start by checking the fuel pump and pressure of the fuel system. That vehicle has no sensor for fuel pressure, so the computer doesn’t know what the actual fuel pressure is. So, if the pump goes bad, the computer doesn’t know and can’t set a trouble code. And on that Blazer, if the pump has to be replaced (and the fuel tank removed to access it), be SURE to check the connector and wiring going into the top of the fuel tank to the in tank pump. That connector and wiring often goes bad. I’ve been burned before by not paying close attention to that connection and had to do the whole job over because of bad wiring back there. It’s a simple job to check once you have the tank pulled, and no one wants to do that job twice.

99 Chevy S-10 Heater Repair

Toby’s question:

” recently bought a 99 Chevy S- 10 from a small dealer. During the test drive the heat blew out only cold air and only out the dash vents, not the floor or the defrosters but the AC compressor was kicking on. The dealer made me a great offer on this truck partly because I told them I would fix the heater myself figuring it was just a vacuum leak. 50 miles into the trip home it suddenly switched to blazing hot heat coming out and would not go back to cold. Now I have found a nasty vacuum leak and repaired it and the controls are working great now, defrost, floor and dash vents. However it is still stuck on heat, after taking the dash apart I found this seems to be electrical, I took it apart as far as I am comfortable and the door between hot and cold is staying on the hot side no matter where I have the control. There is a fuse in this circuit, I know because I dropped the plug and blew the fuse, so I know the fuse is good. What is my next step?? Do I replace the dash controls? Or the mechanism that moves the flap door? If it’s the latter, how do I get it out of the dash? Or is there something I missed? I’d rather do the work myself than deal with a dealership if at all possible. Any help would be appreciated Thanks in advance, Toby”


Your blend door is stuck. Sometimes you can try to get inside there and lubricate the door, as they are plastic and sometimes just stick. I realize there is little working room in there, BUT if you can, lots of guys will just break off whatever is holding the door in the heat position and then just put a coat hanger or even an old fashioned hand choke assembly on that blend door so they can open and close it manually. That way you don’t have to mess with all that electronic crap which breaks quite frequently on those Chevys. I see it all the time. many times you end up buying the entire heating assembly to fix it correctly, and that isn’t cheap, so bypassing those stupid controls is an option. Actually fixing those electronically controlled systems really can only be done by a professional mechanic, unless you want to just guess with some VERY expensive parts.

2001 Silverado Fuel Tank Switch

Andrew’s question:

“My 2001 Silverado has two gas tanks. One works, the other just stays full of gas. What can I check to make them both work again?”


There’s a switch that makes the tanks change from one side to the other on the dash. I haven’t seen any of those switches go bad, but I have seen a few of the relays that operate the fuel cross over valve go bad. I’d check that relay first as it’s a more common problem.

2000 Chevy Astro van’s fuel gauge problems

bob’s question:

“My 2000 Chevy Astro van’s fuel gauge always reads full when I turn the van on. When I just use turn the key half a turn so the battery turns on the interior the gauge reads low fuel. Also my interior dome light does not go on when doors are open. It works when the light switch is turned on. I noticed that the previous owner had wire running to the rear of the van for some lights on a trailer. Could this be the problem? Where do I start looking? Thanks”


Odds are you’ve got more than one problem there. The fuel gauge can be a bad sending unit, a bad dash unit, a problem in the wiring, OR a problem in the small computer that runs the dash (called body control modules OR General Electrical Modules.) Since your gauge reads full when the vehicle is running, but empty when you just have the key on and the engine not running, I doubt that it’s the sending unit in the tank. It would read the same as long as power exists in the circuit, whether the engine was running or not. I would assume you have a problem in your dash, in the dash wiring, OR in the general electrical module in the dash. Tracing it down will be no fun, so why not just fill your van up and reset the trip odometer and then just fill it up again when you’ve gone your usual refill distance (say every 250 miles.) That won’t cost you anything. As for the dome light, you’ve probably got a short in the wiring or switches that go to the doors, as the light works when you turn its switch on. So check all the doors and back hatch to see if you’re getting power to the switches and check the switches to see if they work when they’re turned on and off. Good Luck.

2006 Impala LS hissing noise coming from the vehicle

Alan’s question:

“I have a 2006 Impala LS. Yesterday I noticed a slight hissing noise coming from the vehicle. It’s like some metals grinding each other with rhythm and the problem is only obvious at the between 20-35 mph. I guess it is from the rear wheel on the driver’s side. I cannot hear it if I close the window or drive at speed higher than 40. What could it be and how can I pinpoint the problem?”


Pull off the rear wheels and check to see if anything is rubbing, you’ll see rub marks in the area that’s hitting stuff. Also check the rear brakes to make sure the pads aren’t just worn down to the metal. Most noises in the back will leave telltale rub marks, so look closely when you pull off the wheels, inside the rims and where the tires may be rubbing against body work.

1984 Chevy Caprice shifter does not return to position after pulling into gear

Ted’s question:

“My son just bought a 1984 chevy caprice w/auto trans.The shifter does not return to position after pulling into gear. Is there a spring broken? Im afraid it might slip into gear if left idle in park. How do I fix?”


More commonly, the shifter linkeage gets bent OR the shifter cable that goes from the shifter to the transmission is just worn out. After all, it’s just a small cable that’s been tugged at for twenty four years in that vehicle. So check that cable first.

94 Chevy S-10 Blazer Stalling On Idle

Andrew’s question:

“I have a 94 chevy s-10 blazer. It makes a clicking noice when I start it. When I am driving and go to stop it makes a clicking noice and stalls. It acts like the motor wants to run but the tranny or something stops it. I am thinking that it might be the flywheel or torque converter. Can I please get your opinion.”


Those flywheels are cheaply made with spot welds and often come apart and wobble, causing noise. And eventually they can wobble enough to wreck the torque converter and cause stalling. Pull the starter off and have someone manually turn the engine 360 degrees while looking in the starter hole. Then you can see if it’s wobbling and you’ll have to pull the transmission off then to fix it.