But, any persistent noise should be investigated. Some noise will be the result of rust on the rotors, calipers, hardware or even the brake pads themselves. Use only the best parts, replace questionable units and make sure that the brake hardware is in good condition or new. Also, make sure that all the metal-to-metal contact areas are being lubed with the proper grease that’s designed to do this tough job in a harsh environment.
The rotors come into play again if you’re faced with a brake-related vibration. The most common is a vibration while braking that’s caused by warped rotors. Ask your customer a couple of questions that could help ensure a quality job: When did you notice the problem, and what happened to cause the problem? Did you have any tire work done lately? If so, it’s likely you’ll find that the lug nuts are unevenly tightened. To confirm this condition, loosen the lug nuts by hand. More often than not, the over-tightened nuts will be obvious.
The biggest enemy of the rotor is heat, so take a good look at the rotors as they’re removed for signs of overheating. It makes little sense to install fresh parts only to subject them to the same conditions. It could be that the last tech who did the brakes missed one of the steps we just talked about, or, more likely, the increased mileage has caused a problem. Either way, if it’s not corrected, your new rotors will soon be in the same shape as the ones you just took off.
With high-mileage vehicles, you could be faced with a “brake pedal sometimes fades to the floor” complaint. Although it’s not a common complaint on Nissans, a little detective work is required in such cases. If the pedal fades as the vehicle comes to a stop, often in a situation where the pedal is being partially applied in anticipation of coming to a full stop, it’s a safe bet the master cylinder is the culprit.
If, on the other hand, the condition results from a long ride at highway speeds, it’s likely that excessive drag is causing the fluid in the calipers to overheat, resulting in brake fade. When the brakes cool, the pedal often will return to what feels like normal to the customer. Many times, the customer will report a burning smell and the worst cases will cause a severe vibration. It takes a stuck caliper to generate the degree of heat needed to cause these problems, and they certainly should be closely checked.
You should be able to find the problem wheels by inspecting the rotors. If that much heat was generated, the rotors will show the signs. If you can duplicate the tight wheel, don’t be too quick to condemn the caliper without cracking open the bleeder to be sure there’s no pressure in the line. If pressure exists, backtrack through the hydraulic system until the restriction is found.
Nissan uses an emergency brake that is incorporated into the rear caliper. We know that most hand-brakes are not used on a regular basis, and we also know that a mechanical device doesn’t like to sit around, only to suddenly be forced into service. The same thing can be said for the cables. If the hand-brake levers aren’t returning on the caliper, be sure that the cables aren’t binding. The complexity of the hand-brake does make the rear calipers a little pricier, but I still like to replace them in pairs to maintain the balance of the brake system.
Drum Brakes
We’ve been talking about disc brakes, but many Nissans you’ll encounter will be equipped with rear drum brakes. More than adequate to perform the job, they’ll give many miles of service, requiring little attention other than periodic cleaning to remove the dust, and shoe replacement.
The same good brake service habits apply here. Clean, inspect and lube all components, check the hardware and replace what’s necessary with high-quality parts. Be sure that the self-adjusting hardware is working properly, and that the hand-brake cables and associated parts are operating smoothly and are well lubricated.
Don’t overlook the wheel cylinders. Be sure that the pistons are free with no sign of leakage. Be careful not to over-adjust the rear brakes. On the Quest minivan, for example, there is a service bulletin advising that the rear brakes not be adjusted at all. In such cases, let the self-adjusting system handle the task. If they are manually adjusted, they’ll be too tight, causing drag and overheating, and producing all the negative results we’ve been talking about.
ABS Issues
Nissan has done such a good job with its anti-lock brake systems that problems could be considered rare. I’m sure we’re all familiar with ABS operation, and Nissan doesn’t do it any differently. Wheel speed sensors send an AC voltage signal to the underdash ABS control unit, while the brake light signal tells the unit the brakes are applied. If the wheel speed sensor signals brake lockup, the control unit activates solenoid valves in the underhood ABS actuator, controlling the pressure to the locking wheel, preventing a loss of traction and keeping the driver in control. Since the system spends most of its time waiting to be called into service, we want to be sure it’s ready when the driver needs it. It monitors itself for faults and will keep the on-dash ABS lamp illuminated if any problems are found.
If you’re faced with an illuminated ABS lamp, no special tools are required to access codes in Nissans built before 2006. But a scanner with ABS capabilities will certainly make it easier and more efficient. Before retrieving codes, drive the car over 20 mph for at least a minute. I’d even suggest a slightly longer ride that will let you assess overall brake operation.
To retrieve codes on 2000-’06 cars, ground terminal nine in the OBD II diagnostic connector. On earlier models, ground terminal 4 in the Nissan diagnostic connector that’s located next to the fuse box. Codes are counted out on the ABS lamp: They’re two-digit codes with long flashes being tens, followed by short flashes for the ones. For example, one long flash followed by two shorts is 12. When you access the system, the first code you’ll get will be a 12, followed by fault codes if they are stored. Up to three codes will be saved, with the most recent fault being the first displayed. A code 12 will follow the faults. If only a code 12 is found, the system sees no faults. On later model Nissans, an enhanced scanner is required to access ABS and traction control codes and data. The good news is there are plenty of options available at almost any price point that will give you the capabilities required.
