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Camry generations five and six: A brief tour of the Toyota Camry fuel and EVAP systems

In the other test, the PCM reads atmospheric pressure (there’s a “baro” sensor inside the PCM) with the engine running and the VSV and CCV both closed. If pressure inside the canister goes below atmospheric pressure, the PCM decides the VSV is stuck open. A pending code will be recorded in memory, and if this happens on two consecutive trips, the PCM will illuminate the MIL and set code P0441 (purge flow incorrect).

The CCV is tested the same way. With the CCV commanded closed (turned on) and the VSV commanded open, the PCM expects to see high vacuum in the canister. If not, the CCV is not closing. When the canister is at atmospheric pressure and both valves are commanded open, the PCM expects to see no pressure change in the canister. If the canister develops negative pressure for more than four seconds, the CCV is not opening. A pending code will be recorded, and if this happens on two consecutive trips, the PCM will illuminate the MIL and set code P0446 (vent valve circuit malfunction).

The vent passage goes through a filter and terminates in the fuel filler tube. Toyota says the filter can become clogged, but EVAP codes have also been caused by spider nests in that passage.

To leak-test the fuel tank and EVAP system, the PCM simply closes the CCV and opens the VSV to draw a vacuum on the system with the engine running. After closing the VSV, it measures the time required for the vacuum to decay. If there is a leak, the rate of pressure rise determines which fault code will be set: P0442 (large leak) or P0456 (small leak) or P0455 (gross leak). This is also a two-trip test that sets a pending code on the first failure and a hard code on the second consecutive failure.

Figure 3: (A76844) EVAP schematic for the 2002-2006 Camry.
<p>Figure 3: (A76844) EVAP schematic for the 2002-2006 Camry.</p>

Sixth generation

The next (sixth) generation Camry is the 2007-2011 model. The 2AZ-FE engine carries over with the same fuel injection system, but now the C/OPN relay coil shares a power circuit with the injectors. There’s also a new 3.5-liter 2GR-FE six-cylinder engine.

This is the first year that the EVAP system has a dedicated Leak Detection Pump (LDP). All of the other components and most of the operating strategy remain the same, except for the leak test.

The EVAP system leak test runs only if there are no codes or pending codes for the valves. After the engine has been turned off for five hours (to let fuel tank pressure stabilize), the PCM wakes up, reads ambient pressure, turns on the CCV to close the vent, then operates the LDP. Remember, the purge valve is normally closed, but in this system, closing the CCV doesn’t actually seal the system; it connects the LDP to a 0.020-inch reference orifice. Air flows out of the canister through the reference orifice while the PCM monitors the decrease in canister pressure. If it decides there is a leak, it sets a pending code. If the test is failed again after the next drive/rest cycle, the PCM will illuminate the MIL and store the appropriate leak code(s). There are also sensor failure codes (P0450, P0451, P0452, P0453) plus a number of Toyota-specific codes for the valves and pump.

The EVAP monitors can be commanded to run with a scan tool, which is good because it’s possible for local conditions to prevent it from running automatically. If battery voltage falls below 10.5, the test will be aborted. If coolant temperature is not between 40 and 95 degrees F (4 – 35 degrees C) within five hours after shut-down, the PCM will wait two more hours and try again. A third attempt will be made after another 2.5 hours. If pressure altitude is greater than 8,000 feet, the monitor will not run.

Incidentally, the LDP makes noise when it runs, which sometimes causes customers to ask why their car is making strange noises while parked in the garage overnight.

Smart key

The sixth generation Camry is the first available with an optional Smart Key system that has an Engine Start button in place of an ignition key.

The Smart Key system adds a major layer of complexity because some engine operations are controlled by what Toyota calls the main body ECU (aka body control module or BCM). The fuel pump is still operated by the C/OPN relay, and power for that relay’s contacts still comes from the main EFI relay. However, power for the C/OPN relay coil comes from a third relay labeled IG2 (ignition 2) that also provides power to the injectors. Power for the IG2 coil comes from the BCM when the Smart Key is detected.

On the Smart Key system, the BCM and the PCM control the starter together. When the Engine Start button is pushed, various on-board control units verify that the correct key has been detected in the vehicle, and then accessory power is turned on by the BCM. When the Start button is pressed with the gear selector in Park or Neutral and the brake pedal depressed, the BCM activates both ignition relays, unlocks the steering and sends a “start” request to the PCM. The PCM will then request a cut in accessory power (from the BCM) while it activates the starter relay. Once engine speed reaches 1,200 rpm, it will release the starter relay and terminate the accessory-cut request.

If the brake light switch or circuit fails, the engine can still be started by pressing the engine Start button once to turn on accessory power, then pressing it again and holding it for 15 seconds. If there is no fuel in the tank (or if the fuel gauge sending unit fails), the start sequence will not be initiated.

Figure 4: EVAP schematic for the 2007-2011 Camry.
<p>Figure 4: EVAP schematic for the 2007-2011 Camry.</p>

Registering (programming) new keys is the most common issue with this system. It’s usually easy and it can be done with aftermarket pass-through tools. Once you’re in the right section of the Toyota Information System (TIS) website, the process is menu-driven and takes only a few minutes. You can register new keys or keys that had previously been used in another vehicle. However, if you only have a valet key and not a master key, you’ll need a locksmith identification number (LSID). It’s also easy for key registration to fail. Toyota notes that only one key should be in the car during key registration: If there’s more than one, they will interfere with each other and prevent the process from running to completion.

The key registration process was updated last year (July 2014). Toyota Service Bulletin 0043-14 describes new security requirements to obtain a smart key reset pass-code, and the instructions for this new process must be reviewed before attempting to get the pass-code. The TSB also describes how to reset a vehicle immobilizer and/or smart key system.

Service bulletins

Since we’re on the subject of TSBs, don’t forget there were many bulletins and recalls to address accelerator pedal issues on all Toyota models. Here are some of the other important service bulletins covering the fifth and sixth generation Camry.

TSB-0122-08 describes why some smart keys tend to use up their battery quickly. The smart key “wakes up” upon receiving a “ping” or query signal from the BCM, but other electronic devices also emit signals that may activate the smart key. These include certain video devices, computers and monitors, cell phones and cordless telephones, microwave ovens and even some light fixtures. The only fix is to keep the smart key at least three feet away from other electronic devices.

TSB-0003-09 says a faulty “Engine Start” button may cause intermittent no crank/no start on vehicles with smart key. The bulletin describes a diagnostic procedure and includes part numbers for replacement buttons.

Service Campaign SC90K was launched to replace the oil supply line for the camshaft actuator on the six-cylinder engine. The rubber part of that line can develop a leak big enough to turn on the oil pressure light. Parts or repairs are free if the work is performed at a Toyota dealer before the end of 2021(no mention of reimbursement for work done elsewhere).

Safety Recall SC-C0M130213-007 was issued to cover all 2007–2009 Toyota models, but not all VINs (the National Highway Traffic Safety Administration (NHTSA) recall number is 12V491000). The master power window switch tends to stick or develop a “notchy” feeling over time. If that switch is lubricated with “commercially available” lubricants, it may overheat and melt or even catch fire (evidently there were lubrication “irregularities” at the factory). The recall bulletin describes how to disassemble, lube and reassemble the switch using the special grease (04002-18242) and applicator syringe. You’ll need some new one-way screws (04002-18342) to reassemble the switch.

The next generation Camry has even more changes, including a new 2.5-liter engine and lots of new electronic features on the control screen. It will be a while before these models appear in your service bay, but it’s never too early to start learning about them. ●

Thank you to the technicians at MotoLOGIC for their help in preparing this article. –Ed.

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