Service Slants

Toyota

Brake pedal pulsation, vibration. Owners of 2000-05 Tundra pickup trucks may complain of a pedal pulsation and/or vibration through the steering column when the brakes are applied on the open road. While warped front rotors are always a possibility, out-of-round rear brake drums are just as likely a cause, says Toyota.

Start your diagnosis by taking the truck on a road test and applying the brakes a few times to confirm that the pulsation/vibration problem exists. If it does, get the vehicle back up to 40 to 50 mph and slowly apply the parking brake. Don't overdo it; you could lock up the rear wheels! Apply the brake just enough so the rear shoes engage the drums. If you don't feel the bad vibes when the parking brake is applied, the problem is in the front brakes. Machine or replace the front rotors as necessary. If a pulsation/ vibration does set up as you apply the parking brake, the problem is in the rear braking system.

Before replacing the drums, however, check the diameter of the centering area on both rear axle shafts with a vernier caliper or micrometer, as shown in the illustration at right. The diameter should be 4.171 to 4.173 in. If it's larger than that, the drum(s) could run oblong on the shaft(s), says Toyota. Replace the axle shaft(s) as necessary.

If the axle shaft specs are on the money, that confirms that the rear brake drums are warped or out-ofround. New-design, more rigid drums with greater mass are now available from Toyota, and they go by Part No. 42431-34021. Always replace the drums in pairs.

GM Truck

Engine ping or knock, flashing MIL, misfire DTCs logged. Some 2004-05 Chevy Colorado and CMC Canyon pickups with the 2.8 and 3.5L engines (VINs 6 and 8) built on or after VIN breakpoint 58261313 may produce a pinging or knocking sound, possibly accompanied by a flashing MIL. GM says the noise occurs most frequently on deceleration after the engine reaches operating temperature, and is most likely the result of sticking exhaust valves.

To make a definitive diagnosis, hook up your scan tool and start searching for codes. If all you see on the display is P0300 (random misfire) or individual misfire codes P0301 through P0305, that confirms that the valves are indeed hanging up. Installing upgraded exhaust valve springs (Part No. 12596078) and valve stem seals (Part No. 12596994 for the 2.8L engine, 12596501 for the 3.5) should put an end to all the problems in short order.

Ford

No air conditioning. Owners of 2005-06 4.6L Mustangs may come into your shop complaining that the a/c system blows warm air. If the system has a full refrigerant charge, no fuses are blown and the compressor clutch won't engage, chances are good that the clutch has gone belly-up, says Ford. Installing a new clutch assembly and revised orifice tube, then recharging the system to a new refrigerant spec of 26 oz., should bring the cooling performance back into check. After you're done with the parts swap, you'll need to fill out a climate control information decal and affix it underhood to alert the next tech who works on the car of the installation.

Here's a list of the new parts you'll need to complete the fix:

Component Part No.

Clutch disc .........6L2Z-19D786-A

Pulley ..............6L2Z-19D784-A

Clutch coil.........4L3Z-19D796-AA

Orifice tube .......F5XZ-19D990-AB

Information decal . .6R3A-19A286-AA

Saturn

Low or fluctuating idle. Owners of 2004-06 ION Redline models with the 2.OL supercharged inline Four engine (VIN P) may come into your shop complaining of a low or fluctuating idle speed that occurs immediately after the engine is started, hot or cold. If hooking up your scanner turns up no DTCs and there are no other driveability issues noted, flashing the PCM with updated software should improve the idle quality markedly. You'll find the new software calibration on Saturn Service Stall version TIS 6.5 2006 or later.

Ford/Ford Truck

Inoperative a/c system. The air conditioning systems on some 2002-06 Ford cars and light trucks with the FS-10 compressor may not blow cold enough or may not work at all. If you attach your a/c gauges, you'll probably find that the system pressures are way below normal. Ford says a leak at the compressor shaft seal is the likely cause of the undercharge condition. Removing the clutch and installing a new-design, more durable shaft seal (Part No. F1VY-19D665-A) is the permanent fix.

Vehicles that can benefit from the updated seal are 2002 Lincoln Blackwoods; 2003 Ford Escorts, Explorer Sports & Windstars; 2003-05 Ford Excursions, Explorer Sport Tracs and Mercury Sables; 2003-06 Ford Focus, Mustangs, Taurus, Escapes, F-150s, F-Super Dutys & Rangers; 2004-06 Ford Freestars and Mercury Montereys; 2005-06 Mercury Mariners; and 2006 Lincoln Mark LT models.

Toyota

Engine runs hot or overheats. The owner of a 2004-06 Solara with a 3MZ-FE V6 may come into your shop with a complaint that the engine runs hot or overheats on the highway. If that happens, go on a road test with the customer driving, noticing where he places the transmission shifter. If he places it in "S" (manual shift mode), chances are he's got the tranny in 3rd gear. That might be okay at 30 mph in city driving, but it's hell on the open road at 60 mph because the engine will really be screaming.

Toyota has a preventive fix in the form of a revised PCM calibration. The new software will automatically upshift the transmission to 4th gear in manual mode, even if the owner selects 3rd gear on the shifter. To install the new software, order calibration 30642199 for the main ECU, 50621100 for the sub ECU.

GM Truck

Ticking, chirping noise under instrument panel. Drivers of 2005-06 Chevy Colorado and GMC Canyon pickups may come into your shop complaining of a ticking or chirping sound that emanates from underneath the right side of the instrument panel. A noisy blower motor is the most likely source of the irritation. Installing a special insulating cover (Part No. 15836647) directly over the blower should drastically reduce the noise, or eliminate it entirely.

To install the cover, begin by removing the passenger door sill and kick panel moldings, then the floor courtesy light. Working from underneath the dash, disconnect the BCM harness connector at the motor, then disengage the retaining clip from the harness. Now flex the insulating cover and carefully position it over the motor. If it's installed properly, one hole in the cover will align with a hole at the rear of the motor, while a second hole will match up with a stud on the blower motor. Reposition the cover as necessary.

Once the cover is properly installed, secure it to the blower motor with a push-pin type fastener (Part No. 10098645). Now route the BCM harness over the cover and button it down with the existing retaining clip. To complete the fix, install the courtesy light and the kick panel and door sill moldings.

Acura

MIL on, DTC stored. All 2004-05 RSX models, as well as 2006 models built from VIN JH4DC5...6S000001 through TH4DC5...6S000342, are susceptible to illuminating the MIL and storing DTC P1077 (intake manifold runner control/tuning malfunction) in PCM memory. One likely cause for the code, says Acura, is a sticking intake manifold runner control (IMRC) solenoid. Replacing the IMRC solenoid with an upgraded design (Part No. 36163-PND-A01) should eliminate the trouble.

Before installing the upgraded solenoid, clear the code from computer memory. Now install the new solenoid, start the engine and hold the throttle at 3000 rpm until the cooling fan comes on. If the MIL stays off, you're done with the fix, and you can release the car to the customer. If the MIL comes back on and the P1077 logs in computer memory again, further diagnosis of the intake runner system is necessary.

Ford

Oil leak. Ford reports that some 2002 4.6L, two-valve Mustangs (build date prior to 5/17/02) are prone to leaking oil from the top of the engine. If you get one of these leakers in your shop, immediately head for the PCV valve because there's a good chance the stack-up tolerances between the valve and hose may be off-kilter just enough to cause oil to flow out between the valve and hose. Installing an ordinary worm-type clamp onto the hose should stem the tide of lube in a hurry.

Saturn

Inoperative instrument panel backlight. The owner of a 2007 Sky roadster built prior to VIN breakpoint 7Y102344 may come into your shop complaining that the instrument cluster backlighting doesn't work when the headlights are turned on manually during daytime driving. If he does, tell him that the situation is normal. According to Saturn, the backlighting is not controlled by the headlight switch, but rather through a photocell that determines the ambient light conditions necessary to turn on the backlight of the cluster.

If the customer really wants the situation corrected, the good news is that you can offer to reprogram the BCM with an updated service calibration. The new software uses the input from the headlight switch to activate the backlighting to full intensity during the daytime hours. You'll be able to find the revised software on TIS2WEB.

Volkswagen

Air suspension warning light on, DTC stored. Some 2004-06 Touareg SUVs may illuminate the air suspension light on the dash and store DTC 01772 008 in computer memory. The trouble code refers to an "implausible signal of pressure sensor," in Volkswagen lingo. In plain English, it means there's a leak somewhere in the system. Here's a diagnostic procedure that should help flush it out quickly:

Start by detaching the air suspension compressor from its mounts. Using a soapy water solution or an ultrasonic tester, leak-test all the lines at the compressor and valve block. It's best to wiggle the lines to simulate actual driving conditions. If there are no obvious leaks at the compressor and valve block, trace the lines back to each individual air spring and look for leaks or kinks. Repair or replace the lines as necessary.

If everything looks good at this point, it's time to do a leakdown test of the system. Start by putting the truck on a level surface. Next, start the engine and let it idle for 10 minutes with all the doors and the liftgate closed. That will allow the system to fully pressurize. Shut the engine down, then disconnect the electrical connector from the air suspension control module, which you'll find at the right rear quarter panel. Measure and record the dimension from the top of each tire to the wheel well opening. Now allow the truck to sit for at least 12 hours.

After the 12-hour hiatus, again measure the distance from the tires to the top of the wheel well openings to see how much the suspension dropped. A 2 to 3mm drop is normal; anything over 5mm means there's a leak at that particular corner. Check the line from the air spring back to the valve block. Repair or replace the line as necessary. If more than one corner dropped more than 5mm, the valve block probably has an internal leak. Replace it.

If the system passes the leakdown test, check for leaks in the blue lines from the compressor to the accumulators. Be forewarned: These lines aren't easily accessible. You'll have to remove the rear seat and peel back the carpeting to get to them! One difficult leak to find is a poor line seating condition at the rear accumulator. Wiggle all the lines and repair or replace them as needed.

Now start the truck and drive it around a bit. If the warning light stays off, you're done with the fix. If the light comes back on and DTC 01772 008 resets, the air compressor most likely has an internal leak. Don't replace the compressor, it's expensive! Instead, rebuild the internals using a repair kit (Part No. 7LO 698 030).

Ford Truck

Fluid leak from front axle. Owners of 1995-2005 Ford trucks and SUVs (complete list below) may complain of fluid leakage from the front axle. One likely cause for the leak, says Ford, is fluid from the differential gears being thrown toward the axle vent during normal driving. The accumulated fluid then exits the vent tube and drips onto a driveway or garage floor while the vehicle is parked.

Installing a revised front axle cover from a kit (Part No. F6TZ-4033-BA) should stem the tide of lube. The new cover features special baffles that help redirect the fluid away from the vent during operation. The kit comes with installation instructions, but don't use them, warns Ford. Instead, follow the procedures outlined here:

Start by placing the transmission in Neutral and getting the truck up on a lift. Next, remove the engine splash shield, if so equipped, and place alignment marks on the front pinion flange and driveshaft. Remove the driveshaft bolts and retainers and toss the bolts. Now tape the U-joint bearing caps and swing the driveshaft away from the pinion yoke. secure the driveshaft to prevent it from dropping.

Continue by removing the three axle support mounting bracket bolts from the axle housing, then place a screw-type jack stand under the housing. Next, get a couple of shop rags and place them over the torsion bars to protect the halfshaft boots from damage. Now remove the two bolts and nuts from the axle support bushings and toss the nuts. Using the jack stand, slowly lower the axle housing until it rests on the torsion bars. Disconnect the vent hose from the housing, position a drain pan under the axle cover and remove and discard the cover. Clean the axle cover mounting surface with brake cleaner, then apply a continuous bead of RTV sealant Trom the kit onto the sealing surface. Install the revised axle cover, along with the new vent hose and clip from the kit. Now tighten the cover bolts to 22 ft.-lbs. and connect the new vent hose to the existing vent hose using the supplied inline connector. Remove the old vent from the axle housing and tap it off using the pipe plug included in the kit.

Now it's time to put everything back together. Start by raising the axle with the jack stand. Once it's in position, install the axle support bushing bolts along with new nuts, which you should torque to 49 ft.-lbs. Now install the axle support mounting bracket to the housing and tighten the bolts to 78 ft.lbs. Reconnect the driveshaft to the pinion flange, making sure the marks you made earlier are aligned. Torque the new bolts to 14 ft.-lbs. To complete the repair, remove the axle housing fill plug, fill the differential with 3.25 pints of Motorcraft 80W-90 gear oil or an equivalent and reinstall the fill plug.

Vehicles that are prone to the fluid leakage and can benefit from the new-design baffled cover are 1995-2001 Ford Explorers, 1997-2001 Mercury Mountaineers, 1997-2005 Ford Ranger pickups, 2001-03 Ford Explorer Sports and 2001-05 Ford Explorer Sport Tracs.

Nissan

Squeak from rear. Some 2004-06 Titan pickup trucks built before 8/24/05 may produce a squeaking sound from the rear suspension when going over speed bumps and similar type road surfaces. According to Nissan, the noise can emanate from one or both sides of the vehicle, and is most likely the result of the leaf spring wind-up clip cover(s) rubbing against the side(s) of the spring. Installing new-design covers (Part No. 54099-ZH30A, two required per side) and new flat-head screws (Part No. 01412-0009U) to hold them in place should eradicate the noise in no time.

As with most leaf spring repairs, you're going to have to work with the suspension loaded. That means getting under the truck with a creeper or, more preferably, putting the big rig on an alignment rack. Once the truck is in position, start the parts swap by removing the retaining screw from the wind-up clip. Next, push in on the positioning disc in the center of the plastic cover to release the cover from the clip. Pull up on the cover, slide it off the wind-up clip and toss it. Now push in on the disc of the new, revised cover and slide it down over the clip. Repeat the entire drill for the other plastic cover. Install the flat-head screw to retain the covers, making sure you peen the side opposite the head with a chisel to hold it in place. To complete the fix, repeat the procedure on the other leaf spring, then take to the road to ensure the squeaking noise is gone.

Cadillac

Loss of Reverse. The owner of a 2003 CTS model with the 5L40-E transaxle may complain that the car won't move in Reverse. According to Cadillac, the problem may be accompanied by an illuminated MIL, with DTC P0722 stored in computer memory. A shorted pulse-width-modulated TCC solenoid is a likely culprit.

To check things out, begin by looking up the build date of the car. If it's on or after 2/10/03 (VIN breakpoint 849522), this fix doesn't apply; continue troubleshooting the no-Reverse complaint. If the build date is before 2/10/03, get the car on a lift, remove the drain plug and examine the transmission fluid. If it's burnt, the tranny will have to come out of the car for disassembly. If the fluid looks okay, remove the transmission pan and drop the valve body to gain access to the TCC solenoid. Now remove the solenoid and look at the build number stamped onto its connector. If the number is 2690, the solenoid is probably shorted internally, says Cadillac and you should replace it with an upgraded solenoid (Part No. 96042599).

Now it's time to reinstall the valve body. Torquing the valve body bolts to the proper spec and in sequence is critical to proper transaxle operation. If you tighten the bolts any old way, the valve bores will distort and cause the shift valves to stick. Consult a manual for the proper sequence, then tighten the eight inverted Torx bolts to 97 in.-lbs. Now tighten the manual detent spring bolt to the same value. Install a new transmission filter, followed by the pan. The pan gasket can be reused.

To complete the repair, lower the car, fill the transaxle with fresh fluid, start the engine, place the gearshift in Reverse and check for proper engagement.

Mini

Brake lights stay on. Drivers of 2002-05 Mini Cooper, Cooper S and convertible models built up to 3/05 may come into your shop with a complaint that the brake lights stay on all the time. In certain situations, other electrical gremlins may manifest themselves, as well.

One probable cause for the electrical miscues, say the folks at Mini, is water leaking into the interior of the vehicle and infiltrating key connectors, wiring splices and components. The source of the water is a clogged or mispositioned evaporator drain.

Start your repair by replacing or repairing affected connectors, splices, switches, components, etc. Grab some wiring schematics and let the symptoms be your guide to exactly which circuits require your attention. Once all the electrical issues have been sorted out, look for a pinched wiring harness in the area where the evaporator housing meets the cowl. The harness may be preventing the evaporator drain hose from seating properly in the hole in the body where condensate escapes. If you see a harness in the area, relocate it away from the evaporator drain. Finally, check for and remove excess sealer in die area of the evaporator drain and body hole.

GM Truck

Brake warning lamps illuminated. Some 2003-05 Chevy Silverado and GMC Sierra 2500- and 3500-series HD trucks may illuminate both the ABS and Service Brake System warning lamps on the dash. The problem typically occurs on initial start-up, is usually intermittent in nature, is more likely to surface on trucks with a diesel engine (though it can occur with gas engines, as well) and won't store a hard DTC in computer memory.

A timing issue related to the cranking/starting regimen is the likely cause of the bogus warning lamps, says GM. Reprogramming the Electronic Brake Control Module with updated software should eliminate the annoyance immediately. You'll find the updated files in TIS software version 7.5 or later.

Honda

MIL on, evap DTC stored. The owner of a 2007 Fit model may come into your shop one day alarmed that the MIL is on. If he does, hook up your scanner and start poking around for DTCs. If the only code you come across is P0451 (fuel tank pressure sensor range/performance problem) and the car was built between VINs JHMGD3...7S000001 and JHMGD3 ...7S017916, the PCM may simply be misinterpreting the pressure sensors input signal, says Honda.

To make a definitive diagnosis, take a look at the VSS parameter in the freeze frame data. If the code set at greater than 5 mph, continue with normal troubleshooting. If the code stored at under 5 mph, the pressure sensor's signal is being skewed by the engine management system. Reprogramming the PCM using HDS software version 2.005.008 or later should wipe out the code and turn off the MIL immediately. Here are the specifics on the software:

PGM-FI Program ID PGM-FI Program Part No.

MEA140 or later ... .37805-RME-A14

MEA659 or later ... .37805-RME-A65

MEA850 or later ... .37805-RME-A85

Ford

MIL illuminated, lean exhaust DTCs stored. Some 1996-98 Ford Contours and Mercury Mystiques with the 2.OL 4-cylinder engine may turn on the MIL and log lean exhaust codes P0171 and/or P0172 in PCM memory. One possible cause for the illuminated MIL and lean codes, notes Ford, is a contaminated mass airflow sensor. A revised, better-quality MAF sensor (Part No. F5RZ12B579-B) is now available to address the concern.

To determine if the new sensor will do any good, hook up your scanner and start hunting for codes. If DTCs other than those above are stored, take care of them first. After that, or if the only code you pull is the P0171 and/or P0172, start your diagnosis by checking the air induction system for leaks or obstructions. If everything looks good, start the engine and allow it to reach normal operating temperature. With all accessories off and the transmission in Park or Neutral, note the barometric pressure reading on the scanner display. It should be within ±8Hz of the normal reading for your altitude. Next, look at the output voltage from the MAF sensor. It should be no greater than .70 volt. Finally, take a peek at the PID for long-term fuel trim. The reading shouldn't exceed -12%. If any two of the three specs are out of range, install the new, revised MAF sensor with confidence. If most or all are within bounds, grab a repair manual and follow Pinpoint Test H for either of the two lean DTCs.

GM Truck

Whining noise while turning or braking. Drivers of 1999-2002 Chevy Astro and GMC Safari vans may come up to your write-up desk complaining of an irritating whining sound from the power steering system that occurs when turning the wheels or hitting the brakes.

One likely cause of the noise, says GM, is a restriction in the inlet hose between the steering pump and hydraulic brake booster. Swapping out the old hose for a new design (Part No. 15094588) should quell the ruckus immediately. To prevent the new hose from kinking, make sure it's routed under the brake lines and behind the outlet hose at the booster.

Copyright Hearst Business Publishing Jul 2007
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