Chevrolet S10 Lurches Forward While Slowing/Stopping

[Josh Keller]

1999 Chevrolet S10 LS (2.2L, Automatic, RWD, Short Bed, Regular Cab, 231,000 Miles).

Hello, new to the forum and I am trying to diagnose an issue with my Chevrolet S10. It slightly lurches forward when the brakes are applied to slow down or stop. It is very slight. I would describe the feeling to be similar to a vehicle with warped rotors. I “think” the issue is with the transmission (4L60E) or torque converter. No service engine soon light or stored codes. I am thinking that the torque converter may not be fulling disengaging. No decrease in engine RPM when the lurch occurs. Engine has never stalled during the lurch either. Transmission is the factory build. No slipping and it shifts quietly, smoothly and the torque converter locks up.

I serviced the transmission less than a year ago (ACDelco Dexron VI Fluid, ACDelco Pan Gasket, and ACDelco Filter). Fluid looked and smelled like new and was at the proper level. Transmission pan magnet was and has also been very clean during services. I decided to service the transmission again about a month ago and replace the torque converter clutch solenoid, thinking it may be the issue. I also replace the 1,2 and 3,4 solenoids and the torque converter pulse width modulation solenoid. New filter, fluid, and pan gasket as well. All parts where GM or ACDelco. Unfortunately, the lurch is still present.

I don’t think it is chassis related (worn control arm bushings, engine mounts, rear end axle/leaf spring wrap, end yoke, universal joints, etc.). What leads me to believe this is, if I accelerate the vehicle up to 45 mph (torque converter is locked), remove my foot from the accelerator, allow the vehicle to slow to about 20 mph, shift the transmission into neutral, and then apply the brakes to slow down and stop, the lurch is not present. The brake pedal is solid with normal travel, and no vibrations can be felt or noises heard.

I am early to apply the brakes and I apply the brakes lightly (just my driving style). I have applied the brakes with more force to determine if the lurch is still present, and it is, but is slightly less noticeable.

Any ideas? Am I on the right track to diagnosing the issue? Just a note, I am the second owner of the vehicle. I purchased the vehicle when it was three years old and I was 17 (2002). Still my daily driver 19 years later. All maintenance has been performed by me.

Appreciate the ideas and help.

 

[AutoMechanic]

Last few times I’ve worked on something that was lurching forwards it ended up being brake calipers sticking. I’m sure it could be other things but I would check if they are sticking first.

 

[spasm3]

Sounds a little like the TCC solenoid. But usually it stalls out the engine as you come to a stop. Basically the torque converter does not unlock and its like a manual trans coming to a stop without the clutch depressed.

 

[Josh Keller]

Appreciate the replies.

It could be a sticking caliper. I replaced the rotors, pads, hardware, and wheel bearings about two years ago. All four corners were bled as well. Brake pad wear was even. Would a sticking caliper (pins) or sticking caliper piston be noticeable in the brake pedal? Maybe I will remove the front wheels this weekend and inspect everything. Calipers and lines are factory, but appear to be in good condition.

I did replace the TCC solenoid. I had to splice it into the existing wiring harness (no plug like the other solenoids). The lurch feeling is still present though.

 

[AutoMechanic]

Appreciate the replies.

It could be a sticking caliper. I replaced the rotors, pads, hardware, and wheel bearings about two years ago. All four corners were bled as well. Brake pad wear was even. Would a sticking caliper (pins) or sticking caliper piston be noticeable in the brake pedal? Maybe I will remove the front wheels this weekend and inspect everything. Calipers and lines are factory, but appear to be in good condition.

I did replace the TCC solenoid. I had to splice it into the existing wiring harness (no plug like the other solenoids). The lurch feeling is still present though.

You could feel it in the pedal most of the times. Also it could be just the lines too the soft ones that run into the calipers sometimes they collapse on the inside then function more like a valve and let fluid through but not back up which would also cause the calipers to stick too.

 

[Nick1994]

Coast to a stop in neutral and see if it makes a difference.

 

[tasch72]

Appreciate the replies.

It could be a sticking caliper. I replaced the rotors, pads, hardware, and wheel bearings about two years ago. All four corners were bled as well. Brake pad wear was even. Would a sticking caliper (pins) or sticking caliper piston be noticeable in the brake pedal? Maybe I will remove the front wheels this weekend and inspect everything. Calipers and lines are factory, but appear to be in good condition.

I did replace the TCC solenoid. I had to splice it into the existing wiring harness (no plug like the other solenoids). The lurch feeling is still present though.

Most likely not related to your brakes, but it wouldn't hurt to re-grease your pins and check for abnormal wear. Caliper issues will generally pull your car to one side or the other when braking.

It would probably be worth taking a look at your idle air control valve and throttle body. If they're all gunked up, they might not be helping the situation.

I'm all about checking the free, cheap, and easy solutions first when diagnosing problems, and checking all this would probably cost you an hour or two of time, a dollop of sil-glide, and half a can of carb clean.

 

[clinebarger]

Do you have the ability to scan live data? If so.....Monitor the Brake Switch PID, It should change states when the brake pedal is depressed.

There are 2 separate switch contacts within the brake light switch.....One is for the brake lights which is normally open, Then another for the Torque Converter Clutch & Cruise Control which is normally closed. This side of the switch cancels Cruise & TCC apply.

*Does the Cruise Control cancel with brake pedal input???
*If you don't have Cruise.....The Purple Wire at the Brake Switch should have 12vdc with the brake pedal relaxed & NO voltage with it depressed.

 

[Josh Keller]

Coast to a stop in neutral and see if it makes a difference.

Most likely not related to your brakes, but it wouldn't hurt to re-grease your pins and check for abnormal wear. Caliper issues will generally pull your car to one side or the other when braking.

It would probably be worth taking a look at your idle air control valve and throttle body. If they're all gunked up, they might not be helping the situation.

I'm all about checking the free, cheap, and easy solutions first when diagnosing problems, and checking all this would probably cost you an hour or two of time, a dollop of sil-glide, and half a can of carb clean.

Do you have the ability to scan live data? If so.....Monitor the Brake Switch PID, It should change states when the brake pedal is depressed.

There are 2 separate switch contacts within the brake light switch.....One is for the brake lights which is normally open, Then another for the Torque Converter Clutch & Cruise Control which is normally closed. This side of the switch cancels Cruise & TCC apply.

*Does the Cruise Control cancel with brake pedal input???
*If you don't have Cruise.....The Purple Wire at the Brake Switch should have 12vdc with the brake pedal relaxed & NO voltage with it depressed.

Drove to the office for work today (mixed interstate and city) and collected some more data.

Coasted to a stop a few times with the transmission in neutral and there was no lurching sensation. There was no lurching sensation when accelerating the vehicle to about 25 miles per hour, shifting the transmission into neutral and braking to stop the vehicle.

I replaced the factory idle air control valve and throttle position sensor less than two years ago, when I changed spark plugs and spark plug wires. Nothing wrong with the idle air control valve or throttle position sensor other than being 19 years old. The throttle body was fairly clean, but I did clean it, but I did not remove it from the intake manifold. I used throttle body cleaner and some towels.

I do not have the ability to scan live data whit the scan tool I have. I may just spend the money and invest in a more functional one. Driving to the office on the interstate this morning, I used the cruise control (always do). The cruise control functions correctly. Rate assist functions and the cruise control is canceled if the brake pedal is pressed while the cruise control is set.

When I exited the interstate, I left the transmission in drive and coasted to the stoplight and stopped the vehicle using the brakes. No lurching sensation. Vehicle was parked in the parking garage for about eight hours until I drove home. Leaving the parking garage and coasting down the ramp and dragging the brake (transmission in drive), I could feel the lurching sensation. Every stoplight and stop sign I stopped at with the transmission in drive on the way home, the lurching sensation was noticeable. It appears to only occur when the transmission has shifted into first gear. The lurching sensation is not occurring in third or second gear. Shifting the transmission into neutral when stopping eliminates the lurching sensation. No noises heard or vibrations felt via the brake pedal. Maybe the torque converter is beginning to fail. Any ideas?

 

[supton]

It doesn't sound like a brake issue, but the usual test is to take a drive, several miles, then gently come to a stop, so as to not heat up the brakes from braking. Then CAREFULLY place your hand near the rotors on all four wheels. Any dragging caliper will result in a rotor on one corner that is hotter than the others. [In this case you may have rear drums but the concept is the same.]

Couple years ago I had a dragging rear caliper and it would cause a bouncing, but it was at like 40-60mph, it was rather weird. In your case, it sounds more like transmission, but I do not know what, sorry.

 

[wolfox03SS]

A bad brake hardline to the rear axle can also make the rear lurch, wiggle or shake on brake application too. It feels like a bump that makes the truck steer a little sideways too. So check for leaks back there and your soft hoses. If you have the three channel ABS, have a shop bleed and cycle your ABS unit to make sure it's clean and functional.

Other than that? Jack it up, make sure that your suspension bushings are still there and your body bushings too. I *think* if I remember right, the S10 is Chevy's smallest ladder-box framed truck. The body rests on bushings that look like hockey pucks. If they're bad, it too can cause the whole cab and/or bed to also shift with a solid shake as you decelerate and thump your rump a bit.

Edit: Last minute thought here. How's your spare tire winch doing? A slack cable just lets your spare free ball under the bed and can also give you a good thump 'n' bump if it's so slack that it moves.

This transmission and engine combo isn't known for many issues. It's a solid piece of work. Most common failure modes in the mini- truck is stupidly hard 1-2 upshift and then the engine bogs. Or when reversing one day, ping! No traction at all on forward and reverse due to a fractured sun shell reaction gear housing. If you can? Try to scan the computer for any pending codes, especially transmission codes. If any are there it is mainly likely ECU Trans wiring harness that had a rodent bite on something.

 

[Josh Keller]

A bad brake hardline to the rear axle can also make the rear lurch, wiggle or shake on brake application too. It feels like a bump that makes the truck steer a little sideways too. So check for leaks back there and your soft hoses. If you have the three channel ABS, have a shop bleed and cycle your ABS unit to make sure it's clean and functional.

Other than that? Jack it up, make sure that your suspension bushings are still there and your body bushings too. I *think* if I remember right, the S10 is Chevy's smallest ladder-box framed truck. The body rests on bushings that look like hockey pucks. If they're bad, it too can cause the whole cab and/or bed to also shift with a solid shake as you decelerate and thump your rump a bit.

Edit: Last minute thought here. How's your spare tire winch doing? A slack cable just lets your spare free ball under the bed and can also give you a good thump 'n' bump if it's so slack that it moves.

This transmission and engine combo isn't known for many issues. It's a solid piece of work. Most common failure modes in the mini- truck is stupidly hard 1-2 upshift and then the engine bogs. Or when reversing one day, ping! No traction at all on forward and reverse due to a fractured sun shell reaction gear housing. If you can? Try to scan the computer for any pending codes, especially transmission codes. If any are there it is mainly likely ECU Trans wiring harness that had a rodent bite on something.

Rear hard brake lines appear to be in good condition. No leaks that I could see near any of the connections or at the wheel cylinders.

Body mounting bushings look decent for their age. Only one on the passenger side of the cab appeared to be a dry rotted.

Spare tire and cable are secure.

I will perform a scan function again for any pending codes. None displayed last time I checked. I hope there isn’t a damaged wire from a rodent. Won’t be too enjoyable chasing that down.

I plan to go over the front brakes this weekend to check for any issues. Rear brakes should be good. I replaced the drums, shoes, and hardware about two moths ago.

 

[SatinSilver]

Lubegard Red in the trans may help was my first thought.

 

[Bud_One]

Axle wrap ?

Driveline clunk ?

We used to have to pack drive shaft input shafts with red tacky grease on some older GMC C1500 due to them complaining of a bump when coming to a stop to alleviate the complaint.

 

[Josh Keller]

Lubegard Red in the trans may help was my first thought.

Appreciate the suggestion. I’ve never tried any transmission fluid additives before. I’ll look into Lubegard Red.

Axle wrap ?

Driveline clunk ?

We used to have to pack drive shaft input shafts with red tacky grease on some older GMC C1500 due to them complaining of a bump when coming to a stop to alleviate the complaint.

I am going to remove the driveshaft and clean the splines of the slip yoke, lube, and reinstall. I’ll be able to more closely inspect the universal joints too. No noises or clunking sounds to note.

 

[another Todd]

Some engines stop injecting fuel when you coast, until you reach a certain RPM then they start spraying again and you can feel a slight lurch as they start spraying again. Won't do it in neutral because they keep spraying to keep the engine running, but in gear it can be felt. It might just be a coincidence that you apply the brake pedal at the same rpm as the injectors start up again. Try coasting down to a near stop from highway speed (SAFELY), in drive, without using the brakes and see if you feel it. It seems to me my Focus did it at about 1500 RPM, but each engine could be different. Might not be anything wrong at all.