The only thing more difficult than working on some of today’s valve bodies is working on them when there’s no information available. Such is the case with the later version of the Subaru 5AT valve body.
According to the manufacturers, if you have a problem with one of these valve bodies, you need to buy a new one… at considerable cost.
No doubt that works for them. But out in the real world, with real transmission technicians, we repair valve bodies. So we’ve come up with a fair amount of information to help you when you come into contact with one of these units.
The valve body we’ll be using came from a 2009 Subaru Tribeca. These units also appear in 2009-on Subaru Legacy and Outback models with 5-speed automatics (5AT).
One of the biggest problems with this valve body is nothing’s available separately: When something goes south, the manufacturer wants you to buy a new valve body. So, if you run into one with a bad pressure switch, range switch, solenoid, or speed sensor, you have two choices: scavenge a core or buy a new valve body.
In this article, we’re going to go over the valve body completely, so you have the information you’ll need to diagnose and fix a problem.
The valve and solenoid names we’ll be using are of our own creation; we’ve named them after their functions. For now, no one else has published any information on this valve body, so we’ve had to set the standards for naming and identification.
These new Subaru valve bodies have eight solenoids; they’re the linear style solenoid, much like the Asian Warner type.
What’s more, all of the solenoids appear to be very similar, so, if you’re planning to remove them, you’ll want to label them first, to make sure you get them back in the right places.
There are numbers in very small print on the plastic parts of the solenoids (figure 1); none of them are the same, so you could use those numbers to identify the solenoids; just remember to record which one went where.
As we mentioned before, none of the solenoids are available separately at this time, so, if you need to replace one, you’ll either have to buy a new valve body or scavenge one from a core.
All eight solenoids measure 5.7 ohms resistance at room temperature.
Now let’s look at each solenoid, one at a time, to see where they are and what they do (figure 2):
Line Pressure Solenoid — Oil from the solenoid assists the pressure regulator spring and closes the pressure regulator valve, increasing line pressure. The line pressure solenoid connector has two yellow wires.
Front Brake Solenoid — Oil from solenoid acts on the front brake accumulator and front brake regulator valves, which send oil to the clutch pack. The front brake clutch can be on in every gear except 4th; it’s usually used for engine braking. The front brake solenoid is controlled through two brown wires.
Lockup Solenoid — Oil from solenoid operates the lockup control valve and regulator. This controls oil flow to the torque converter for lockup operation. The lockup solenoid is controlled through two blue wires.
High and Low Reverse Clutch Solenoid — Oil flows from the solenoid to the high and low reverse control and high and low reverse accumulator valves. The high and low reverse clutch is on in park, reverse, neutral, 1st sport mode, 3rd, 4th, and 5th gears. The high and low reverse solenoid receives power through two orange wires.
Transfer Clutch Solenoid — Oil from the solenoid flows to the transfer clutch control valve and transfer clutch accumulator. This solenoid is active under heavy engine loads and when the computer detects tire slip, to activate all-wheel drive mode. The transfer case clutch solenoid receives power through two gray wires.
Direct Clutch Solenoid — Oil from the solenoid flows to the direct clutch control valve and the direct clutch accumulator. The direct clutch solenoid is active in 2nd, 3rd, and 4th gears. The direct clutch solenoid receives power through two white wires.
Forward Brake Solenoid — Oil flows from the solenoid to the forward brake control valve and forward brake accumulator. The forward brake clutch is on in 1st and 2nd gears. The solenoid receives power through two black wires.
All pressure switches on the Subaru 5AT valve body are normally open and close with pressure. This valve body has five, single-wire pressure switches (figure 3).
The front brake pressure switch closes when the front brake clutch has pressure. This switch has an orange wire.
The input clutch pressure switch closes when the input clutch has pressure. It has a purple wire to it.
The forward brake pressure switch closes when the forward brake clutch has pressure. It uses a blue wire.
The direct clutch pressure switch closes when the direct clutch has pressure. It has a white wire to it.
The high and low reverse clutch pressure switch closes when the high and low reverse clutch has pressure. It uses a yellow wire.
If any of these switches fails to close when the computer expects it to, the computer will go into failsafe mode. At this time, none of the switches are available separately.
It’s surprising to see so many valves with linear type solenoids (figures 4 and 5). Each solenoid controls a regulator valve for the front brake clutch, input clutch, high and low reverse clutch, transfer clutch, direct clutch, and forward brake clutch. And each clutch has an accumulator in the valve to cushion the apply.
The pressure regulator valve is a little different from most valve lineups: It doesn’t have a boost valve. The line pressure solenoid adds oil pressure to the spring side to control line pressure.
The pressure regulator valve also has a pressure modifier valve that sends oil to the opposite side of spring to lower pressure in park and neutral.
This valve body uses two solenoid regulating valves to control the oil pressure to the solenoid. These are very active valves; always inspect the bores carefully for wear.
Solenoid regulator 1 supplies oil to the direct, input, high and low reverse, and transfer solenoids. Solenoid regulator 2 supplies oil to the line pressure, lockup, front brake, and forward brake solenoids.
The TCC regulator and control valves are in the same bore, using a common valve lineup. The control valve switches fluid direction in the converter and the regulator valve regulates converter clutch slip.
CHECKBALLS AND FILTERS
The upper valve body houses the filters, checkballs, and the drainback ball (figure 6). There are four filters to keep the solenoids clean.
There are three checkballs to direct oil through the feed holes. The checkballs are for the reverse, forward brake, and input clutches. There’s also a checkball and spring in the lube circuit to control drainback.
So, there you have it: Everything we’ve come up with about the Subaru 5AT valve body. All this new information should give you a leg up when diagnosing engagement and shift problems on these units.
Special thanks to Arnold’s Transmission & Gear in Denver, Colorado, for sending us this valve body.