Joined
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2 Posts
Two pence…
So there’s a LOT of potential problems/nuances that can cause this type of condition. I’d be willing to bet that most of these issues are one in the same but sadly when there’s an answer for one, it doesn’t fit all. Basically every powertrain and drivetrain fault can generate a hard shift/shock/or clunk. You’ll have to establish a solid baseline for every single vehicle you encounter. For example, starting and charging circuits, if your battery is deficient or your alternator doesn’t keep up with loads you can experience shift problems. If you have a check engine light that you’ve driven on for the last two years, it could cause the problem. Anything that loads the vehicle during a shift, like the a/c compressor can cause the problem. Does that mean that those are the solutions? Absolutely not. But if they’re defective it will convey in a shift. Toyota does not specify a service interval for the WS transmission fluid. It’s considered a lifetime synthetic. And well… yes, it causes problems. Since trans fluid is hydraulic, as it breaks down it can’t do its job and you might as well run water through the valve body. The fluid loses its ability to protect parts, becomes saturated in debris(micro-particles) and just like the oil you fry your Christmas turkey or Saturday night footballs French fries(freedom fries… duh) it gets old and needs to be thrown out. Catch 22. New fluid can cause slippage if you’ve waited 250,000 miles to change it, or the act of draining the fluid and exposing clutches to air may. I haven’t seen it happen in quite a long time but it can and does happen. Everything is built with planned obsolescence in mind. Most vehicles are designed to last around 150,000 miles before they need a major repair( engine or transmission). Now, what’s all this mean…. There are a number of ways to isolate a crafty, nasty, dare I say… evil shift condition. Sell the truck, sell it now…. Hahahaha. Just kidding, unless I can get it for about $50. Then it’s definitely a death trap. Moving on, if you drive a 4wd vehicle you can remove the rear driveshaft and lock the front differential in. If it doesn’t clunk/shock then it’s between the transfer case output shaft and the rear wheels. Yes, Toyota has a couple TSB’s related. One says to do the previous test. But what if it’s 2wd…. You’re screwed…. Nope, being a bad technician again. It may be more difficult to isolate 2wd though. A driveshaft defect will usually surface as a clunk during engagement, as in a downshift at a stop or during a downshift from torque converter lockup when the shaft is not driving as much load. But what part of the driveshaft you say? Checking for play in the u joints should be a given but the devils in the details. If you have a center hanger bearing on a two piece shaft, with play, that can cause both conditions of shock(coming to a stop or downshift from lock up). If you have brake drag from the rear, guess what? Stupid condition can manifest again. I’ve spent nearly a quarter century learning to isolate these ghosts and I still get stumped. Very very frustrating. I stumbled upon this forum in a google search for this ghost. Sadly, the cost and time didn’t allow me to finalize a repair that fixed the concern today but these considerations may help you with yours. I pulled the driveshaft on my target, it seemed to minimize the effect, considering how many times I’ve seen fluid cause an issue I was hesitant to pull the trigger on a new driveshaft, as they are quite pricey. I even repacked (very carefully) the slip yoke with grease to help absorb the shock and to allow a “tighter” fit of a part commonly over looked and clearing the vent hole of obstructed grease, didn’t quite cut the mustard. I advised a transmission fluid change to cover the corners and that’s where the bottom fell out. Having already done repairs for state inspection guidelines and paid to pull the driveshaft, the customer wasn’t prepared for the depth of chase. WS is expensive stuff by the way. Many of these things can be done from home and documented to help narrow down problems. The downside is, as a technician you can’t accept that everything was done to a T and sometimes you have to back track over what someone else has done to confirm(beyond any shadow of a doubt) that a part is good. I saw a few posts of folks concerned with getting a torque converter replaced because there may be other damage done. While it is possible, it is very rare at the dealership setting(all reputable businesses will stand behind the work). I wouldn’t fear damage from a factory trained technician. They don’t give transmission jobs to the oil techs. On another note. Having worked for Toyota, I can tell you beyond any doubt and slap a guarantee on it to boot, when a technician hits the button on the factory scan tool and begins their diagnostics, a copy is sent to Toyota of the trouble codes, freeze frame data, date, time, what you had for breakfast, etc and the engineers can pull that information to help isolate a condition. Even if the technician cleared the codes and data before recording it. GUARANTEED. If you have any doubts about a diagnosis you can call Toyota’s customer service line and they will back their product 100%. I’ve seen it multiple times. I’ve seen a non-English speaking Japanese man show up, to plug a computer that I’ve never seen in my life, into a vehicle to isolate a problem that was occurring. Toyota is one manufacturer that does not short change the customer. Dealerships on the other hand, can sometimes push a customer off when they’re under pressure and can’t get work completed(doesn’t happen often but it can). So, finally, what if there are no codes? There usually isn’t for a shock type shift. The computer control system looks for changes in resistance and open or shorted circuits. When none are found, the computer outputs no codes. That’s when a technician has to work from problem symptom tables and experience. Bear in mind, we are human and do make mistakes, and often you’ll find that a tech will spend hours isolating a problem and may not even get paid for a warranty condition that can’t be isolated(I spent about 4 hours in the chase to get paid 1.7 for diag and pulling the driveshaft). It’s the nature of the beast. Just realized that another impact is driveline angle! If you’ve lifted the truck or it has sagged much, you’ll find nuances in shifting. Usually in the form of vibration but sometimes during a shift depending on wear of driveline. So in conclusion, it’s not a cut and dry, plug up a scan tool and get answers situation. It can take hours or days of constant work and a small fortune to narrow down what the root cause is. I’ve only given a few potential sources, there’s probably a hundred more. Be sure to do routine maintenance and catch up things long overdue then you can establish a baseline and if all else fails, go to the junk yard and pick up some cheap parts to try and see if they change the dynamics in any way. Hope my pence help in some fashion. Pennies don’t go far these days… Can’t say that my post does either but this should give you both some ideas and some perspective on what has to be done to isolate a ghost. See ya around!
So there’s a LOT of potential problems/nuances that can cause this type of condition. I’d be willing to bet that most of these issues are one in the same but sadly when there’s an answer for one, it doesn’t fit all. Basically every powertrain and drivetrain fault can generate a hard shift/shock/or clunk. You’ll have to establish a solid baseline for every single vehicle you encounter. For example, starting and charging circuits, if your battery is deficient or your alternator doesn’t keep up with loads you can experience shift problems. If you have a check engine light that you’ve driven on for the last two years, it could cause the problem. Anything that loads the vehicle during a shift, like the a/c compressor can cause the problem. Does that mean that those are the solutions? Absolutely not. But if they’re defective it will convey in a shift. Toyota does not specify a service interval for the WS transmission fluid. It’s considered a lifetime synthetic. And well… yes, it causes problems. Since trans fluid is hydraulic, as it breaks down it can’t do its job and you might as well run water through the valve body. The fluid loses its ability to protect parts, becomes saturated in debris(micro-particles) and just like the oil you fry your Christmas turkey or Saturday night footballs French fries(freedom fries… duh) it gets old and needs to be thrown out. Catch 22. New fluid can cause slippage if you’ve waited 250,000 miles to change it, or the act of draining the fluid and exposing clutches to air may. I haven’t seen it happen in quite a long time but it can and does happen. Everything is built with planned obsolescence in mind. Most vehicles are designed to last around 150,000 miles before they need a major repair( engine or transmission). Now, what’s all this mean…. There are a number of ways to isolate a crafty, nasty, dare I say… evil shift condition. Sell the truck, sell it now…. Hahahaha. Just kidding, unless I can get it for about $50. Then it’s definitely a death trap. Moving on, if you drive a 4wd vehicle you can remove the rear driveshaft and lock the front differential in. If it doesn’t clunk/shock then it’s between the transfer case output shaft and the rear wheels. Yes, Toyota has a couple TSB’s related. One says to do the previous test. But what if it’s 2wd…. You’re screwed…. Nope, being a bad technician again. It may be more difficult to isolate 2wd though. A driveshaft defect will usually surface as a clunk during engagement, as in a downshift at a stop or during a downshift from torque converter lockup when the shaft is not driving as much load. But what part of the driveshaft you say? Checking for play in the u joints should be a given but the devils in the details. If you have a center hanger bearing on a two piece shaft, with play, that can cause both conditions of shock(coming to a stop or downshift from lock up). If you have brake drag from the rear, guess what? Stupid condition can manifest again. I’ve spent nearly a quarter century learning to isolate these ghosts and I still get stumped. Very very frustrating. I stumbled upon this forum in a google search for this ghost. Sadly, the cost and time didn’t allow me to finalize a repair that fixed the concern today but these considerations may help you with yours. I pulled the driveshaft on my target, it seemed to minimize the effect, considering how many times I’ve seen fluid cause an issue I was hesitant to pull the trigger on a new driveshaft, as they are quite pricey. I even repacked (very carefully) the slip yoke with grease to help absorb the shock and to allow a “tighter” fit of a part commonly over looked and clearing the vent hole of obstructed grease, didn’t quite cut the mustard. I advised a transmission fluid change to cover the corners and that’s where the bottom fell out. Having already done repairs for state inspection guidelines and paid to pull the driveshaft, the customer wasn’t prepared for the depth of chase. WS is expensive stuff by the way. Many of these things can be done from home and documented to help narrow down problems. The downside is, as a technician you can’t accept that everything was done to a T and sometimes you have to back track over what someone else has done to confirm(beyond any shadow of a doubt) that a part is good. I saw a few posts of folks concerned with getting a torque converter replaced because there may be other damage done. While it is possible, it is very rare at the dealership setting(all reputable businesses will stand behind the work). I wouldn’t fear damage from a factory trained technician. They don’t give transmission jobs to the oil techs. On another note. Having worked for Toyota, I can tell you beyond any doubt and slap a guarantee on it to boot, when a technician hits the button on the factory scan tool and begins their diagnostics, a copy is sent to Toyota of the trouble codes, freeze frame data, date, time, what you had for breakfast, etc and the engineers can pull that information to help isolate a condition. Even if the technician cleared the codes and data before recording it. GUARANTEED. If you have any doubts about a diagnosis you can call Toyota’s customer service line and they will back their product 100%. I’ve seen it multiple times. I’ve seen a non-English speaking Japanese man show up, to plug a computer that I’ve never seen in my life, into a vehicle to isolate a problem that was occurring. Toyota is one manufacturer that does not short change the customer. Dealerships on the other hand, can sometimes push a customer off when they’re under pressure and can’t get work completed(doesn’t happen often but it can). So, finally, what if there are no codes? There usually isn’t for a shock type shift. The computer control system looks for changes in resistance and open or shorted circuits. When none are found, the computer outputs no codes. That’s when a technician has to work from problem symptom tables and experience. Bear in mind, we are human and do make mistakes, and often you’ll find that a tech will spend hours isolating a problem and may not even get paid for a warranty condition that can’t be isolated(I spent about 4 hours in the chase to get paid 1.7 for diag and pulling the driveshaft). It’s the nature of the beast. Just realized that another impact is driveline angle! If you’ve lifted the truck or it has sagged much, you’ll find nuances in shifting. Usually in the form of vibration but sometimes during a shift depending on wear of driveline. So in conclusion, it’s not a cut and dry, plug up a scan tool and get answers situation. It can take hours or days of constant work and a small fortune to narrow down what the root cause is. I’ve only given a few potential sources, there’s probably a hundred more. Be sure to do routine maintenance and catch up things long overdue then you can establish a baseline and if all else fails, go to the junk yard and pick up some cheap parts to try and see if they change the dynamics in any way. Hope my pence help in some fashion. Pennies don’t go far these days… Can’t say that my post does either but this should give you both some ideas and some perspective on what has to be done to isolate a ghost. See ya around!
