P0732 engine code

P0732 - Gear 2 Incorrect ratio

This is typical of a slipping clutch pack. There's two common causes of that. The first is a cut rubber lip seal on the piston. The more common cause of that is worn fiber plates in the clutch pack. The way to identify that is by reading the "clutch volume index", (CVI). I use a Chrysler DRB3 scanner for my vehicles. I suspect other high-end scanners will do that too.

This chart applies to one version of transmission in your van. Pay particular attention to the volumes for the low / reverse clutch and the 2 / 4 clutch. If you find a CVI value close to the maximum listed, it's time for a rebuild.

The CVIs are calculated by watching the input speed sensor and output speed sensor signals to determine when one clutch pack releases and the next one locks up. The time it takes is used to make that calculation. One trick that often works to verify a clutch pack is taking too long to lock up is to accelerate harder than normal to cause a delay in an up-shift, then release the accelerator pedal long enough to let that up-shift occur under low torque. That will reduce the slippage so it won't be detected, and won't go into limp mode. That can allow you to get into the higher gears, but it only delays the inevitable for a few days or weeks. The rebuild is the permanent fix.

"CVI" is "clutch volume index. That is a two-digit number that corresponds to the volume, in ccs, of fluid it takes to apply each clutch pack. My training goes back to the '89 models that were four-speed computer-controlled transmissions. Chrysler was the first to introduce them, as they were for most innovations that benefitted car owners. Today every manufacturer has their own versions.

With the older hydraulically-controlled automatic transmissions that were around since the '50s, as the clutch plates wore down, it took more and more fluid to apply those clutch packs. As that occurred, we observed a little "engine runaway" during upshifts, meaning it was like the transmission went into neutral for a fraction of a second. That slippage gave us up to two or three years notice that a rebuild was in its future.

One of the advantages of the computer-controlled transmission is the computer continually learns those volumes of fluid it takes to apply the clutch packs, and as the plates wear, it takes more and more fluid. Based on those updated values, the computer will turn on second gear, for example, a little sooner, before it releases first gear. That overcomes engine runaway and makes for a nice crisp shift just like when the vehicle was new, ... Until the day comes when it can't update any further. Once that day comes, you had a nice solid shift yesterday, but today the excessive slippage gets detected and the computer puts the system into "limp" mode to allow you to drive slowly to a repair shop without needing a tow truck. The wear has been taking place for years, just like before, but you don't get the few years of warning like before.

Two speed sensors are involved with this slippage. One is the input speed sensor which is after the torque converter, and the output speed sensor on the tail shaft. The Transmission Computer has the gear ratios for each gear programmed in. Based on that and the gear it is in, it knows for a given input speed, the output shaft had better be going its calculated speed. It knows there's excessive slippage in a clutch pack when those two speeds don't agree. When excessive slippage occurs, besides going into limp mode, it will set a diagnostic fault code for, "incorrect gear ratio" for the specified clutch pack.

Limp mode keeps the transmission in second gear. You also have reverse, neutral, and park. To get it out of limp mode, the ignition switch must be turned off, then the engine restarted.

Going into limp mode is caused more often by sensor and other electrical problems than with the clutch packs. It's important to understand, as with engine or other systems, fault codes never say to replace a part or that one is defective. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a sensor or other part is referenced in a fault code, it is actually the cause of that code only about half of the time. First we have to check for broken wires, corroded connector terminals, and mechanical problems associated with that part as part of the diagnostics before we condemn the part.

Diagnostic fault codes are stored in the Transmission Computer, and it will tell the Engine Computer about those codes. In response, the Engine Computer sets fault code P700 which just means there's codes in the Transmission Computer. The Engine Computer has its own set of well over 2000 potential fault codes. About half of them refer to things that could potentially adversely affect emissions. Those are the codes that turn on the Check Engine light. P700 turns that light on because staying in second gear will result in using for fuel than normal.

I have a Chrysler DRB3 scanner for most of my vehicles. I've used it to read the clutch volume index a few times, but you'll have to consult a transmission specialist to find out what normal readings are.

Also, if you don't know the fault code numbers, you can get an idea of the cause of going to limp mode by observing when it occurs. If it is related to a sensor, wiring, or something else electrical, that may be detected as soon as you shift into "drive". It will go into limp mode right away and you'll start out immediately in second gear.

If the defect is related to clutch plate wear or internal fluid leakage, it will start out in first gear like normal, and up-shift at the right times, until the defect occurs. Most of the time it will bang back to second gear during or right after an up-shift, but it can also happen during down-shifts when slowing down.

There is a potential work-around when slippage is occurring during an upshift. If you notice it goes to limp mode during a shift from, lets say third to fourth gear, accelerate harder than normal while still in third gear, to get to a higher speed, then let off the accelerator pedal to reduce the torque, and let the transmission ooze into fourth gear. After giving it a couple of seconds to lock up solidly, you can accelerate further to highway speed. People have been able to delay transmission rebuilds for months by doing that.

You should consider reposting your question by starting a new one specific to your vehicle. This one was a private conversation between just two people. As such, none of the other experts got an automated e-mail message directing them back here, so they never got to see your addition or have a chance to reply. Many times that won't get you the help you need. You're stuck relying on my wondrous wisdom.

If you do start your own question, please be sure to list the engine size, mileage, type of transmission, and any other details. We look at the engine size to find the right wiring diagrams and component layout drawings. I use the mileage to figure out the list of best suspects for some problems.

Happy to share my wondrous knowledge. I saw your new post with lots of dandy details. Expect to get some good answers tomorrow.

I too have never seen the designation, "preliminary" What I can share is any time the battery is disconnected, those learned CVI values are lost. The computer reverts back to the initial starting values programmed in at the factory, then it could shift like a race car for the next two miles or dozen shift cycles until it relearns that data.

From my tv / vcr repair experience, I learned that when a company needs an integrated circuit designed and produced for a new product, it takes about six months for them to show up. When Chrysler started producing the four-speed transmissions for the '89 models, the first ones were hand-assembled, and were really tough and reliable. When they started coming down the assembly line on the first day they went into production vehicles, 12 of the first 30 exploded when they tried to drive onto the test rollers just before going outside. They stopped the line to investigate, and found that while up-shifting, it would lock into a new gear before it unlocked the previous gear. That would have been fine for a very high-mileage transmission, but even those that snuck through that initial set of shifts could do the same damage months later if the battery had been disconnected. Two internal rotating masses going at different speeds were locked to the housing at the same time. The torque broke the housings.

They figured out the cause of the problem, made design changes to one integrated circuit, and had the revised parts from the supplier the very next day, not six months later. Some of the employees popped the covers off the Transmission Computers, replaced that IC, popped the covers back on, and handed them to the assembly line workers as fast as the vehicles came down the line. They lost less than one day of production, but no more exploding transmissions.

In the first few model years, those transmissions suffered a lot of failures due to "tolerance build-up". Unlike those first ones that were hand-assembled, in production, a groove for a snap-ring could be allowed to be off just a little. A machined sealing surface also could be off just a little. A dozen other things had a small range of variation that was considered normal production tolerances, but if you ended up with a group of parts all off on the same side of "perfect", you could get a shaft that with just a little normal wear would no longer sit under a sealing ring. The leakage would get detected and the computer would put it in limp mode. Both Chrysler and the aftermarket industry came up with a lot of revised parts to address that problem, so today, if you have one rebuilt, it can cost more than normal because of all those better parts they want to put in, but then their reliability is as good as any other transmission.