2000 Jimmy 4x4 4.3 SLE 4 door 220K miles. New fuel pump a couple years ago, new battery about a year ago, has never had a tune up but I have the new wires and plugs, just haven't gotten around to it yet. Also have new fuel filter but waiting for that tune up. Have replaced fuel filter within last couple years (I know I know, it needs done more often). Cleaned all the gunk out of throttle body (or whatever this vehicle has) last year because it was bad enough that the gas pedal was getting hard to push....hope that's enough info.

Last time driven was yesterday. Went to start tonight and got nothing but a single click. With key in first position (before turning all the way to start) lights are bright, hear fuel pump kick in, voltage shows good, but when turning to start I just got a single click, gauges would all drop back, voltage drop on battery. Had this happen once before with a dead cell battery, so attempted jump starting. No luck there, just the same single click. I have experienced the extreme cold ignition switch problems, and have learned to adapt the way I start the car, barely turning it to start instead of all the way.....you know if you've been there.

Anyway, it's freakin cold and we have 4 inches of snow, so I was going to wait until tomorrow to work on it, but couldn't resist. Assumed my starter is bad, and after extensive reading online I finally found where the starter is so inconveniently located so outside I went with a tarp, light, and hammer. Finally managed to get the hammer in a position to tap on the starter several times, not an easy task. Still no start, just the click. Tried some more tapping, more starting, no luck. After my 3rd or 4th attempt I noticed the O2 sensor I'd read about that's kind of in the way. The wire for the sensor looked a little suspicious so I wiggled it around, pushed it in on the sensor, made sure the plug was well attached. Tapped a little more aggressively on the starter (getting frustrated). That time when I turned the key, it did attempt to turn over but just cranked and cranked. I did notice a smell, electrical it seemed, or maybe just gas fumes. So I went underneath again, tapped on starter some more in various positions, wiggled O2 connection some more, tried to start again, crank crank, etc. like it wanted to start but just couldn't get there. After one more trip under the car, more tapping, more O2 wire pushing, it finally started up.

The exhaust fumes were very strong smelling. I let it run a couple minutes to try and burn that off, then turned off, and restarted. Still cranked a little before startup, but it did start. I did this a couple more times, each time it started easier. Finally I let it run for awhile to make sure my battery was charged up after all the stress. Eventually strong exhaust smell went away. And it restarted perfectly on next attempt.

So I guess my question is...Does this sound like my starter is definitely bad, or is it possible for that O2 sensor wiring to be bad and causing a problem, or both? The only notable thing I've had happen recently, is that sometimes when I put it in reverse and am backing up slowly, the car dies. It doesn't sputter or anything, just when I get done backing and put it in forward, I realize it's not running anymore....

I would love to hear the O2 sensor is the easy fix since it sounds like the starter is a PITA to get out of there. But break it to me gently. Am I in for a new starter? Any suggestions on further testing I can do before taking the plunge? I've read so many posts where people replaced starters and still had same problems, so hoping to eliminate all that guesswork.

 

Sounds like you have multiple issues going on here. The O2 sensor can't cause what you're experiencing. First need to get it cranking consistently. Take both of the cables off of the battery. Slide the rubber boots down the cables and use a wire brush on the terminals, and on the battery. Make them shine, no green fuzz allowed. Re connect and tighten the cables, and try it. If no success there, follow both cables from the battery, and clean the opposite ends. Same program, shine 'em up, no green fuzz. Post your results.

 

Thanks for your quick reply. I'll try that tomorrow if weather permits. So you don't think any of my thumping around on starter is definitely showing it's bad? I honestly couldn't reach it well enough to hit it very hard...probably a good thing

 

BTW, to clean the opposite end of battery cable, I'm still going to have to remove starter right? Isn't that where the really hard part comes in? Like if I manage to get that end of the cable free to clean, I might as well take starter in for testing?

 

Beating on it with a hammer creates a vibration. The shock wave and wiggling stuff around can travel and affect something else. There's also the element of coincidense and intermittent. So it really doesn't provide the conclussive results that we're looking for. There is a 175 amp fuse under the battery, with a connection at each end of it. A Crappy connection on either end could cause the problem. Clean up those two, and the ground connection to the engine block first. Then we'll see if it's necessary to drop the starter down.

 

Will check that fuse and connections when it warms up later. Is the fuse accessible from underneath, or do I have to remove battery and tray? Having a hard time finding diagram online for a visual aid.

Just remembered another thing that may be from bad connections. Sometimes at night I notice my headlights dim or flicker slightly when applying the brake. Not enough that a passenger has ever noticed. I read one post on here about this on a 97 and they mentioned a small black box on drivers fender well that had some heavy cable connections that were bad. Will see if my 2000 has something similar. Just wish I had a heated garage and a lift ��

 

You'll need to remove the battery and the tray to access the fuse. Besides the battery cables, one bolt holds the battery to the tray, and two bolts hold the tray to the radiator support.

Flickering lights could be normal. The alternator is controlled by the PCM on yours and it uses a pulse signal to excite the voltage regulator, instead of a constant voltage. There is a GM TSB that addresses the issue, but it needs to be diagnosed as being the problem, (could also be a problem with the alternator).

 

No corrosion on Connectors at battery, at the 175 amp fuse, or at the point where the positive hooks into the underhood fuse box. There is a tiny bit of green visible between the copper strands in the cables themselves, where the insulation starts, but no large buildup like I've seen before on another vehicle. The only ground I could get to was the one under battery tray by that big fuse, and it was clean. The other two grounds I couldn't reach. The one at the block is covered with oil and gunk from old leaks so couldn't get a visual even. Looks like I'd have to remove alternator and bracket to get in there. One on frame is clean but was too tight to break loose at the weird angle I was attempting.

Car has started fine several times today. I've heard that starters get a bad or dead spot and will work as long as they don't land on that dead spot when the car is turned off, and that's why thumping on them can break that loose. Is that right? Even though I haven't been able to check all the grounds, when we hooked up and tried to jump start it last night, shouldn't that have eliminated the grounds as an issue?

 

There is such a thing as a dead spot on starters, and that could be the issue. The main ground from the battery is attached to the front of the block. You should be able to get at it. Might have to take the splash shield off though. As for eliminating grounds as a possibility, if you connected the negative jumper cable end to the engine block, that would bypass the main ground connection at the block. If you connected it to the battery terminal, and it started, the main ground might be ok. At least make sure it's tight. The best way to check connections is by checking voltage drop across the connection you are testing.


Voltage Drop Testing

 

I haven't dropped the ball, just haven't had my Jimmy fail to start since that one time a week ago. The start is not always as enthusiastic, a little draggy, but has started every time. I'm carrying my hammer with me and waiting for it to act up again. Don't want to buy that starter until I'm sure! Drove down some bumpy country roads today, maybe if it's a bad ground that will bounce it loose again, or coat it with dust. Have my tester handy also for when/if it fails to start. I'll update when things go wrong again. Just staying fairly close to home right now