Transmission Exchange Co.

28/10/2025

29/01/2025

Getting a Grip on the Aisin AR5 Transmission
By Mike Weinberg

Aisin World Corp. is a large manufacturer of original-equipment automotive components including manual and automatic transmissions. AX5 and AX15 five-speed transmissions have been around for years, and the AR5 is an evolution of those designs. The AR5 is built in rear-wheel-drive and four-wheel-drive models and resembles the AX5 and AX15 designs externally, as well as the Toyota R155 five-speed transmissions

The AR5 is a five-speed transmission, with 5th being overdrive, that is found in 2005-and-up Chevrolet Colorado and GMC Canyon trucks, the 2006-and-up Pontiac Solstice and the 2007-up Saturn Skye. All gears are synchronized, and the shafts are supported by roller ball bearings, while all of the gear train is supported by needle bearings.

This design uses a four-part aluminum case made up of a removable bellhousing, main case, center support and extension housing. The rear-wheel-drive units have an oil trough mounted in the case that moves lubricant to the rear bushing. Unique to this design is an internal oil baffle mounted on the main case that keeps the oil from being thrown around the case. As these units are splash lubricated, this baffle acts to contain the oil onto the gear train for better cooling and lubrication. No shims are required to set end-play, but all retaining snap rings are selective and you should use the thickest one that will fit. These transmissions are spec’d to use a special 75-90W gear l**e, GM part # 89021806, although for better cold-weather shifting you should substitute GM synchromesh fluid.

The shift system is typical AX5/AX15 with a single main shift rail moving four shift rails mounted in the center support. There is a complex detent and interlock system in the design to prevent obtaining more than one gear at a time. Worn detents, interlocks and shift forks produce a variety of shifting problems on high-mileage units, and these should be inspected thoroughly during teardown to prevent comebacks.

The synchronizer assemblies use spring-loaded keys to engage the synchronizer ring onto the cones of the selected speed gear. The clearance level of the synchro ring to the face of the speed gear is listed at 0.031 inch. A surefire way to prevent shift issues, even on rings that meet the spec, is to clean the cones on the speed gears, use a magic marker to color the cone and then, using a known-good ring, twist the ring down on the cone and then look at the pattern it makes. You will find rings that grab only at the top or the bottom or skip around the cone, because you cannot measure a taper accurately. The five minutes it takes to test the rings will be hours of labor saved going forward.

Whenever you disassemble any synchronizer be sure to match-mark the slider to the hub so that it is replaced in the same spot during reassembly. This will always give you the proper direction that the slider was facing when it was removed, and the splines on the hub and slider will go back to the original position to avoid notchy or dragging shifts. For those of you who don’t like to take synchronizer assemblies apart if they feel good, remember that the splines between the inner hub and slider are usually loaded up with metal contaminants that fresh l**e will set loose to ruin the new bearings you just installed. The second reason to disassemble, inspect and clean the synchro assemblies is to look for cracks on the inside of the hub or sliding sleeve that could come back to bite you.

The more things change, the more they remain the same. The AR5 is a cousin to the AX5/AX15

07/01/2025

While in Los Angeles TRANSMISSION EXCHANGE CO. dropped by the Petersen Automotive Museum to check out 'Best in Low'

14/12/2024

Transmission TowHaul Mode Explained

11/12/2024

Shift Pointers: What causes a neutralizing shift going into fourth gear?
by Wayne Colonna

We learned great lesson when using a scope—a lesson that is still relevant to this very day. It had to do with a 2002 Acura RSX using an MRMA five-speed automatic transmission that was neutralizing going into fourth gear. A scan tool pulled code P0780 for a Shift Malfunction along with P0700 AT System Malfunction. The scan tool also revealed correct shift solenoid firing order, especially third to fourth

We then rebuilt the transmission with all new solenoids. After it was installed and taken for a road test, the original complaint of neutralizing into fourth gear remained.

To eliminate the possibility of having missed an internal transmission problem, we attached a lab scope to all the shift solenoids. With this transmission using “clutch to clutch” shift strategy, a transitional shift sequence takes place. In the case of a third to fourth shift, shift solenoid C turns off first initiating the shift transition. And for a split second, all shift solenoids are off before shift solenoid A turns on. The computer utilizes pressure switch input to control clutch overlap through these solenoids for a smooth seamless shift.

With it neutralizing going into fourth gear, we gave special attention to Shift Solenoid A by including an amp clamp on the circuit as well. These solenoids are grounded at the transmission and then through the “High Side Driver-HSD” inside the PCM; it provides approximately 13.7 volts to the solenoid. Shift solenoid C turns off while immediately after shift solenoid A turns on.

The highlighted area of the amperage reading reveals the pintle bump of the solenoid. This indicates that the electric current running through the solenoid’s wire coil produced a strong enough magnetic field that it moved and closed the pintle in the solenoid. In other words, the solenoid is doing its job.

This seems to indicate that the transmission still had an internal problem causing it to neutralize going into fourth gear. In fact, a Pico WPS500 transducer was attached to the fourth clutch tap which showed 0 PSI when shift solenoid A turned on. The fourth clutch is also used in reverse, and it had reverse with full pressure in the clutch. This confirms there is not a leak in the fourth clutch circuit. This would seem to indicate that there is something wrong in the valve body preventing pressure to reach the clutch.

After the unit was disassembled and gone through again, nothing was found. When the unit went back into the vehicle, it still neutralized going into fourth gear. It was decided to change the computer and when it was, the transmission had fourth gear.

What did we miss? This is the great lesson learned.

By concentrating on shift “solenoid A” being the solenoid coming on to make the shift, “solenoid C” was only glanced at and it looked like it turned off and it did have second gear. But a closer look at this signal in the scope showed that this solenoid didn’t turn off completely.

As mentioned earlier, these shift solenoids are driven from the “HSD” inside the PCM with 13.7 volts. When the HSD shuts off, 0 volts must be observed. When the HSD turned off shift solenoid C, voltage dropped to 2.1 volts rather than 0.

This solenoid has a resistance of approximately 14 ohms. Using ohms law, this would equate to 0.15 amps of current draw (2.1vdc / 14 ohms = .15 amps.

This prevented the solenoid’s magnetic field from collapsing, which simply means it remained on rather than turning off. This kept shift valve C inside the valve body in the applied position preventing fourth clutch applying pressure from Linear solenoid B to enter the fourth clutch circuit. And this is what caused the neutralizing shift into fourth gear.

So, indeed there was a valve in the valve body that prevented pressure from getting to the fourth clutch—but it was due to a computer control fault. Scrutinizing both on-coming and off-coming solenoids is essential for a successful diagnostic.

19/11/2024

Intelligence Gone Bad
By Wayne Colonna

The Jeep Cherokee and Grand Cherokee models are both known to have Drive Train Control Module (DTCM) failure. A more recognizable name for this module is a Transfer Case Control Module (TCCM). The earlier 3.6L Grand Cherokee WK body uses an 845RE transmission with the DTCM located under the driver’s seat. The 3.2 Jeep Cherokee KL body uses the 948TE transmission, and the DTCM in this vehicle can be found in the right rear corner of the spare tire compartment.

One of the ways in which a bad DTCM will present itself is finding code U0403 for Implausible Data Received from the T-Case stored in the PCM, TCM, ABS and the BCM. When this occurs, the first step would be to simply do a visual of the connector plugging into the module looking for terminal corrosion or chaffing of the wire insulation in the harness. After that, an inspection for power and grounds. If all looks well, it may be time to change the module. Or maybe not!

An example of this issue:

A 2017 Jeep Grand Cherokee (WK2) 3.6L using with the 850RE transmission with code U0403 stored as well as the transfer case switch was not lighting up. The DTCM (which was still located under the driver’s seat) was not responding to any of its commands. Since the DTCM is known to be a common source of failure, it was replaced. When this didn’t correct the problem, it was decided to check the Transfer Case Control Switch.
There is a 12-terminal connector that plugs into the switch, But only three wires are in this connector: A power wire, a ground and a LIN BUS wire that goes to the Body Control Module.

Terminal numbers can be easily seen in the back of the switch
After checking for power in the harness connector going to terminal 7 in the switch and ground going to terminal 6. It was found that both were good. At this point the the switch was replaced, but when the new switch was plugged in, this hadn’t fixed the problem as none of the lights on the switch would illuminate.

The only wire that wasn’t checked was the LIN BUS, which is a single wire operating on 12 volts. When the LIN BUS was pulled, only two items were on the LIN BUS 1 circuit: The transfer case control switch and the Intelligent Battery Sensor

After unplugging it, the lights in the transfer case control switch began to work.

It was a case of intelligence gone bad affecting LIN BUS communication. Once a new sensor was installed, LIN communication was restored.

Also the vehicle had a new battery and this sensor can easily be damaged when changing the battery. So, it appears that there also needs to be a degree of intelligence when changing the battery so as to not damage the sensor’s intelligence.

05/11/2024

Recently in the TRANSMISSION EXCHANGE CO. parking lot

30/10/2024

Happy Halloween from TRANSMISSION EXCHANGE CO.

29/08/2024

10R140 - classic drivability complaint
by Wayne Colonna

F-350 6.7L Super Duty using the 10R140 beast of a transmission not upshifting when pulling a load only. On light throttle it will upshift, but not as high as tenth gear. Once the throttle was depressed it would downshift and no longer upshift. It displays similar symptoms to when the wrong tire size is used with vehicles that have highly sensitive curve recognition programs. In these applications (such as a BMW), when wheel speed signals indicate the vehicle is in a turn, it will prevent any shifting. If tire sizes are wrong, it can deceive the computer’s logic system in this way preventing an upshift with medium to heavy throttle. But that is not the case here. This is a 10R140 with a classic drivability complaint.

Code P1548 for an Engine Air Filter Restriction. Clearing the code, yet the problem persists. Inspect the filter , it will be loaded with dirt.

There is a restriction gauge located on the upper housing of the air filter assembly. This device measures the vacuum inside the air filter. The more the air filter is dirty or clogged, the higher the vacuum reading. When the airflow in the intake air system reaches the maximum allowable restriction limit, the air filter restriction gauge indicator moves from the yellow bar to the red bar at the base of the gauge

There have been reports that sometime in 2022, Ford eliminated the use of this gauge, so you may not find it; but if you do, it will need to be reset after the cause of the restriction is resolved. If you are an owner of a Ford Super Duty with this gauge, it is recommended that it be checked every 7,500 miles. If the truck is being used in extremely dusty conditions, this should be checked every 500 miles or two weeks—whichever comes first. The air filter will need to be changed when the restriction gauge reads near the change filter line and the gauge is yellow. Once it is in the red, the engine is suffocating, and classic drivability complaints will be present, affecting fuel economy as well.