ABS cycling at low speed and erratic shifting

[chefmike]

I am experiencing some weird symptoms intermittently. My ABS will cycle at low speed (below 20) and is often combined with erratic shifting (which has gotten worse, but is still intermittent).

I can usually clear it all by turning the truck off and restarting. My first thought is grounds/ electrical, as it runs fine 90% of the time.

I will be checking batteries and resistance etc first chance this weekend, but am experiencing ZERO other problems. No problem starting, shifting is smooth most of the time, engine sounds great, etc.

Any quick thoughts (I know... clean the grounds!)?

Thanks all!

 

[THEFERMANATOR]

With ABS AND shifting issues, I would suspect ap roblem either in the VSSB or VSS circuit. First rule of diagnostics is find associated problems, and determine if they can both fall into one problem area. Both of those systems are reliant upon the VSS in the transfer case, and receive the signal from the VSSB. Most common issue is some metal on the end of the VSS. Pull it out of the transfer case and look for any metal filings or debris on it. If you find anything on it, you probably just found your problem.

 

[chefmike]

With ABS AND shifting issues, I would suspect ap roblem either in the VSSB or VSS circuit. First rule of diagnostics is find associated problems, and determine if they can both fall into one problem area. Both of those systems are reliant upon the VSS in the transfer case, and receive the signal from the VSSB. Most common issue is some metal on the end of the VSS. Pull it out of the transfer case and look for any metal filings or debris on it. If you find anything on it, you probably just found your problem.

Great. I will tear in and look at this. I disconnected the ABS and was running fine for a few days (I am really busy right now, of course). This AM, the truck would not shift 3rd to 4th. Pulled over, turned it off, restarted (immediatly), she shifted fine.

Thanks for giving me a place to concentrate. I will also be cleaning grounds, as a quick check showed I am a little erratic from battery to block.

I am sure I will have more questions after I search VSSB and VSS.

I have also been enjoying working on a 1993 camry I got for a couple hundred bucks from a neighbor. Like I didn't have enough projects going!

 

[chefmike]

Ferm wins the prize, as always. I have a 2wd, I pulled the rear output speed sensor on the transmission and it had a build up of metal on the end of the sensor. I cleaned it off and reinstalled it. I did not reconnect the ABS due to time, but will hook that back up soon.

I pulled codes as well:68, 72, 85, 86. I think it was trans slippage, output circuit and I can't recall the others.

I cleared the codes and will drive it. I need to love on the old girl some before winter.

 

[chefmike]

Tranny ran fine until I hooked the ABS back up. ABS activated at low speed, next upshift cycle, tranny was in 2nd and refused to shift.

I unhooked the ABS again. I am going to look for info on testing the VSS input and output (if possible). VSSB would be next suspect?

Any insight is appreciated, especially if the output sensor on the tranny is not the same as the vehicle speed sensor. I could not find another sensor on the driveline though.

 

[THEFERMANATOR]

The VSS is the one in the back of the trans. For 2 wheel drives it is normally refferred to as an output speed sensor.

 

[chefmike]

I still had problems after cleaning it. Threw codes 68,73 and 85. I had different continuity between the input sensor and out put sensor (compared the reading on each between the leads), so I bought a new sensor. New one reads the same as the input sensor.

Truck ran like a champ. It had a hesitation engaging first of the line previously... almost a jerk or a clunk. It is shifting really smooth now. Oh and cleaning my grounds also got rid of the little puff of smoke on starting... maybe there was a glow plug not getting a good feed? Who knows, but I follow the mantra: clean your grounds first!

I hope this info helps someone else chase ghosts.

 

[chefmike]

My girl still is not happy. She keeps going into limp mode. This time it was the Dtc for the pressure solenoid. I guess i will pull the pan and look around.

I am also noticing that it usually if not always has a jump in rpm during the 1-2 upshift... Slipping? A little bit before it goes into limp, it will do this several times. Nothing major, it is subtle, but then limp mode. And i can get out of limp by turning the truck off and back on and it will drive normal.

Should i start looking for a transmission or trans shop? I can do solenoids, etc but dont have much spare time right now.

May sell her. Saw a 6.0 burb 2004 i liked.

 

[Will L.]

I can't pin anything tying into the abs, but I had a problem with my trans like that, found that I had pinched a wire on the internal harness of the transmission from a filter change. Only other thing that comes to mind is ignition switch going bad caused problems with the trans and abs but not together that I remember.

 

[chefmike]

Abs has been good since I changed the output sensor, so I am wondering if it really is the pressure solenoid.

I checked the fluid cold and it looked good. I need to check it hot. I changed it 20,000 miles ago. I need a chance to focus on this...i have been working to get a little camry going. And she is back on the road now, though also with a little trans issue: wont start in first gear in drive.

At least i have 2 vehicles!

 

[Will L.]

When I had my problem, I could manually shift gears at appropriate speeds and use all 4 gears. If I didn't down shift coming to a stop, when I took of it was in 2nd gear limp mode. I drove for some time like that until I found the problem. Just incase you need to drive in the mean time, maybe this will help.

 

[FellowTraveler]

If I remember right the pan sensor for pressure manifold/trans temp combo sensor if defective will cause issues because it can't properly read the port pressures, this maybe it, or?