Service Slants

GM/GM Truck

Door latch freeze-up. Owners of 2003-07 GM cars and light trucks, including 2003-06 HUMMER H2s and 2006 HUMMER H3s, may complain that one or more of their door latches freeze in extremely cold temperatures. According to GM, the freezeup issue is a result of the design of the door latch detent lever coupled with water entering the latch assembly from a car wash or wet road surfaces. Spraying all the latch detent levers in the vehicle with GM Super Lube (Part No. 123446241) should help solve the freeze-up problem permanently.

Before spraying the lube, make sure the strikers properly engage the latches and that there are no obstructions preventing the doors from fully closing. If everything looks good, use a hair dryer to thaw the latch, then apply compressed air to the latch assembly for several seconds to remove all remaining moisture. Referring to the illustration at right, direct the spray tube of the Super Lube into the latch assembly as shown, then coat the slashed area of the detent lever liberally with the lubricant. Make sure you coat both sides of the lever. To complete the repair, operate the door latch several times to distribute the lube, then move on to the remaining latches in the vehicle.

Ford Truck

No tach signal, warning lamps on, no crank after shutdown. Some 2007 Ford Expeditions and Lincoln Navigators may lose their tach signal, with one or several warning lamps illuminated on the instrument panel. In addition, the truck may not crank on the next attempted start-up after shutdown, with the MIL illuminated and DTC P1260 (Theft Detected, Vehicle Immobilized) logged in computer memory.

According to Ford, all these problems could be the result of a bad or intermittent connector leading to one or more of the various CAN modules in the truck-instrument cluster (IC), restraint control (RCM), antilock brake (ABS), transmission control (TCM) or PCM. Determining which connector is at fault is a matter of connecting your scan tool or other test equipment to see which modules you can and can't communicate with.

Here are a few of the various scenarios: If you can communicate with the IC module but fail in your attempt with the RCM, ABS, TCM or PCM, check for loose or damaged pins 62 and 63 at both sides of connector C238. Similarly, if you can make contact with the IC and RCM but fail with the ABS, TCM and PCM, check pins 12 and 13 at both sides of connector C212. If your test gear makes contact with the IC, RCM and ABS but draws a blank with the TCM and PCM, check pins 20 and 21 at both sides of connector C146. If you can communicate with all of the modules except for the PCM, check pins 13 and 14 and 20 and 21 at both sides of connector C246.

Continuing, if you can't make contact with any of the modules, grab a few wiring schematics and start troubleshooting the various circuits. Finally, if you can communicate with all of the modules and the symptoms persist, you're likely dealing with an intermittent connection at one or more of the connectors mentioned above. Your only recourse is to check each of the connectors individually to pinpoint which pins may be loose or damaged.

Once the affected pins have been identified and repaired, clear the P1260 code, start the engine and check for any other DTCs that may have stored in the modules.

Chrysler

Interior lighting troubles, fluctuating brake lights. The owner of a 2004 Chrysler minivan (Town & Country, Garavan or Voyager) may comment that the interior lights can't be adjusted with the dimmer switch when the headlamp switch is in the ON or AUTO position. If the vehicle was built between 7/1/03 and 8/11/03, the owner may also complain that the intensity of the brake lights fluctuates when the brake pedal is applied. According to Chrysler, both problems are most probably due to software glitches in the body control module (BCM).

To make a definitive diagnosis, hook up your scanner and look up the part number of the BCM software in the vehicle. If it's 04836966AF or lower, you'll need to flash the BCM with updated files you'll find on TechCONNECT If the software part number is higher than 04836966AF, the new files are already loaded into the BCM. Continue with conventional troubleshooting until the problem is resolved.

GM

MIL on, erratic transmission shifts, poor acceleration. According to GM, all of its 2007 and earlier model cars and light trucks (including HUMMER H2s and H3s) can suffer from seemingly unrelated driveability issues. Among the complaints you might hear are that the vehicle accelerates poorly from a stop, or that the engine bogs or has a limited rpm range. In addition, the transmission may shift erratically or slip. Finally, both the engine and transmission concerns may be accompanied by an illuminated MIL.

Start your troubleshooting as you normally would-by connecting your scanner to the DLC. If the only code you pull is related to the mass airflow sensor, GM recommends heading for the air cleaner assembly and taking a quick look at the type of air filter used. Apparently, quite a few owners are replacing their conventional paper filters with a reusable type with a sponge element. Problem is, they overoil the element. The excess oil then makes its way down the air induction duct and onto the hot wire of the MAF sensor, skewing its signal. And that's what causes all the driveability issues.

To make a definitive diagnosis, switch your scanner to the data stream and look at the MAF sensor PID. If the grams-per-second value is extremely low, the hot wire is probably loaded up with coked oil. Clean or replace the MAF sensor, then recommend to the owner to either go back to a conventional air filter or become more judicious with the oil can.

Mitsubishi

Shudder or vibration at steady throttle. Some 1999-2003 Mitsubishi cars and SUVs (complete list below) can produce an irritating shudder or vibration at steady throttle. According to Mitsubishi, the complaint is most noticeable in the 35- to 50mph range, and is most likely due to problems with the torque converter damper clutch. Burnt or overheated transmission fluid is the ultimate villain. Installing an improved fluid with a lower coefficient of friction (type SP-III) should help eliminate the driveability issues.

To make a definitive diagnosis, hook up your scanner and go on a long road test. Drive the vehicle until the transmission fluid reaches at least 158°F, then wait until the shudder or vibration appears. When it does, look at the TCC duty cycle PID on the scanner display. If it's not between 45% and 55%, look for other problems, such as a misfire, tire vibration, front axle troubles or internal transmission or transfer case damage, if applicable.

If the surge or vibration does occur in the duty cycle range noted above, drain the old fluid, flush the tranny cooler, then refill the transmission with the new lube to the FULL mark on the dipstick. Now get back on the road and drive the vehicle. Mitsubishi says it may take up to an hour for the improved fluid to permeate the clutch linings. If the surge or vibration continues after that point, replace the torque converter.

The following vehicles are susceptible to the surge or vibration and can benefit from the upgraded SP-III ATF:

1997-2002 Mirages

1997-2003 Diamantes

1999-2003 Galants & Montero Sports

2000-03 Eclipses

2001-03 Eclipse Spyders & Monteros

2002-03 Lancers

2003 Outlanders

Ford

Hesitation on acceleration. Some 2005-06 Mustangs may hesitate on acceleration, but only after a long, sustained cruise on the highway. According to Ford, the strange condition is most likely the result of air bubbles forming around the fuel pump module while in the cruising mode. Once the car is off the open road, the air bubbles then break loose and get ingested by the fuel pump. The combination of air and fuel in the pump then makes its way to the injectors, which causes the hesitation issue. Installing a new-design fuel pump module (Part No. 7R3Z9H307-C) should eliminate the bubble formation and take care of the driveability problem immediately.

Chevrolet

Finicky fuel gauge. The fuel gauge on some 2005 Corvettes may jump around erratically, or read EMPTY when there's still plenty of fuel in the tank. A Low Fuel message may also be displayed on the driver information center, with DTC P0463 or P2068 stored in computer memory.

According to GM, all these symptoms could be the result of the fuel level sensor overtraveling its ink path. The overtravel condition causes the sensor to temporarily lose electrical contact, which drops the gauge to EMPTY. As fuel is drawn out of the tank, the sensor reestablishes contact with the ink path and the gauge reading returns to normal.

The solution GM has come up with is to reprogram the PCM with updated software. The new software effectively adds an electronic buffer to the gauge circuit, which delays the gauge response while the overtravel situation is occurring. You can find the new calibration on TIS satellite update 11.5.

Jeep

Steering shimmy. Some owners of 1997-2006 Wranglers may complain of a shimmy through the steering wheel, especially after hitting a bump at highway speeds. One likely cause of the trouble, says Jeep, is a bum steering damper.

Before getting out your puller, though, check the balance of the front wheels. Also make sure that the rest of the front suspension is good and tight. If everything checks out okay, install a new-design steering damper (Part No. 52088959AB).

Ford Truck

Humming noise from engine compartment. Some 1997-2004 Ford Expeditions and 1998-2004 Lincoln Navigators, all equipped with air suspension systems, may produce an annoying humming sound that seems to emanate from the engine compartment. One likely source of the ruckus, reports Ford, is an excessively noisy air suspension pump.

Installing parts from a new air suspension pump noise-suppression kit (Part No. 4L1Z-5Z205-AA) should eliminate further trouble. Included in the kit are a redesigned pump mounting bracket, noise-suppressing isolators and installation instructions. The kit helps prevent metal-to-metal contact between the pump and mounting bracket and the inner fender and radiator support-the chief contributor to the noise complaint.

Acura

Bogus brake warning light and DTC set. Some 2007 MDX models built from VIN 5J8TB....7A000001 through 5J8TB....7A008495 may illuminate the amber brake warning light on the dash and store DTC Pl 131 (electric vacuum pump system related sensor malfunction) in computer memory. If the brake system is operating properly and the only code you pull is the P1131, chances are you're dealing with snafus in the brake system software, reports Acura.

To make a definitive diagnosis, hook up your scanner and write down all the DTCs stored. Normally, a Pl 131 will set only if there's also a code relating to one or more of the following sensors: MAP, BARO, VSS or APP (accelerator pedal position sensor). If any of these additional codes are stored hard, follow the respective trouble trees until the problem is resolved. If the only code stored is the Pl 131, that clues you in that the brake system software needs to be updated. To do it, you'll need an HDS operating at software version 2.006.019 or later. As for the new calibration files, you'll need program ID WCA550 or later and program Part No. 37850-RWC-A55 or later.

Chevrolet

Vibration or shudder at idle. Owners of 2005-07 Corvettes with automatic transmissions may come into your shop complaining of a shudder or vibration that can be felt dirough the steering column when they turn the wheel with the engine idling. Chevrolet attributes the condition to abnormally high pressures in the power steering system. The higher pressures put an extra heavy load on the engine, which in turn causes the idle speed to drop appreciably. It's this lowerthan-normal idle speed that's responsible for the vibration or shudder sensation.

Fortunately, Chevy has the fix covered in the form of a new-design power steering inlet hose. Order Part No. 15903239 for 'Vertes with the FEl or FE2 suspension; 15903240 for models with FE3 or FE4 suspensions. After the new inlet hose is installed on cars with the FEl or FE2 suspension, secure it to the return hose with a special retaining clip (Part No. 88967174). On cars with the FE3 or FE4 suspension, the clip gets secured to the front crossmember with a special screw (Part No. 11609268).

Isuzu

Delayed windshield washer spritz. The owner of a 2006-08 Ascender SUV may complain that the wiper arms have to go through several prolonged cycles before the washer pump delivers enough fluid to clean the windshield. Isuzu says the problem usually occurs when the washer reservoir is below one-third full, and attributes it to the washer pump losing its prime due to the low fluid level. Installing a specially designed check valve into the front washer hose should restore the washer nozzle spritz to your customer's satisfaction. Check with a dealer for the part number of the check valve.

To install the valve, begin by opening the hood, then go to the radiator surge tank at the right front fender and locate the front washer hose. Remove the hose from the retaining clip on the tank, then disconnect it from the barbed plastic fitting. Now grab a pair of pliers and remove the barbed fitting from the other side of the hose and chuck it. Install the check valve into one end of the disconnected hose (it doesn't matter which way you orient it) and connect the other end of the hose to the valve. To complete the fix, resecure the hose to the surge tank, close the hood and check for a proper spritz from the windshield washer nozzles.

GM Truck

Clunking noise. Owners of some 1999-2007 GM full-size pickups and SUVs (complete vehicle list below) may complain of a clunking sound from under the hood while performing low-speed turns, especially on rough road surfaces. One likely cause of the noise, says GM, is a binding intermediate steering shaft. A newdesign I-shaft (Part No. 19153614) is now available to address the issue.

To diagnose the problem accurately, get the truck on a rough road, turn the steering wheel slightly left and right and wait until the noise occurs. When it does, you should also feel a binding or sticking through the steering wheel or column. If you hear the noise but there's no abnormal steering feel, the I-shaft in the truck is probably not the problem. Continue your troubleshooting until the cause is found.

The following vehicles are susceptible to the clunking noise and can benefit from the updated intermediate shaft:

1999-2007 Chevy Silverado and GMC Sierra Classic models

2000-06 Chevy Suburbans & Tahoes and GMC Yukons & Yukon XLs

2002-06 Cadillac Escalades and Chevy Avalanches

2003-06 HUMMER H2s

Ford

Vibration while driving. Some 2007 all-wheel-drive Ford Fusion, Mercury Milan and Lincoln MKZ models may produce a wicked vibration while being driven on the open road. Ford attributes the bad vibes to an improperly indexed or out-of-balance rear driveshaft.

Start the fix by getting the car up on a lift. Now disconnect the driveshaft, reindex it, lower the vehicle and take to the road. If the vibration is gone, you're done. If it isn't, replace the driveshaft with an improved unit, Part No. 7E5Z-4R602-A.

Nissan

Buzzing or whining noise from front of engine. Some 2004-07 Nissan cars and trucks with the VQ35 or VQ40 V6 engine may produce an alarming buzzing or whining sound from the front portion of the engine. According to the Japanese maker, the noise tends to get louder as engine speed increases, and is most likely the result of too much slack in the secondary timing chains. Installing redesigned chains (Part No. 13028ZK00B, two required) and chain tensioners (Part No. 13070-ZK01A, bank 1; 13070-ZKOlB, bank 2) should eliminate the noise in short order.

Models that are susceptible to the problem and can benefit from the updated valve timing parts are 200406 Altimas; 2004-07 Maxima sedans and Quest minivans; and 2005-07 Pathfinder, Xterra & Frontier trucks.

GM Truck

Blower works only on low speed or not at all. Some 2004-07 GM trucks with manual a/c or heater-only systems may exhibit a situation in which the blower motor operates only on low speed, or not at all. A likely cause, says GM, is a burnt blower motor resistor connector. Wiring a new-design connector (Part No. 15862656) into the existing harness and replacing the blower resistor should alleviate the problem immediately.

Start the repair by removing the blower motor fuse. Now lower the hush or close-out panel to gain access to the defective connector. Remove the tape from the harness, then cut the wires as close to the connector as possible. Solder the new connector into the harness, making sure you use the special splice sleeves that come with it. Install the new blower resistor. To complete the fix, connect the new connector to die resistor, reinstall the blower fuse, make sure all blower motor speeds work properly and reinstall the hush or close-out panel.

The following trucks are prone to the blower problem and can benefit from the above fix:

2004-06 Chevy Avalanches, Silverados, Tahoes, TrallBlazers & TrailBlazer EXTs; and GMC Envoys, Envoy XLs, Sierras, Yukons, Yukon Denalis & Yukon XLs

2007 Chevy Silverado and GMC Sierra Classics built before 9/1/06

Infiniti

Leak from underneath vehicle. Owners of 2001-03 QX4 trucks with four-wheel-drive systems may complain about an oil leak from underneath the middle portion of the SUV One likely source of the leak, says Infiniti, is a defective pressure port plug on the upper left side of the transfer case. An upgraded, self-sealing plug (Part No. 31306-2W510) is now available to address the leakage issue. Due to the location of the plug, you'll have to remove the transfer case to get at it. After the new plug is installed, run the truck in Drive on a lift to make sure the leak has been eliminated.

Ford

Noise from front suspension. Some 2000-04 Focus models are prone to producing a creaking, clicking, popping, grinding or rattling sound from the front end while being driven at slow speeds over bumps and/or while turning. Ford has narrowed the cause of the noise to three major trouble spots-loose strut fasteners, loose or worn stabilizer links or worn or out-of-position spring seat sleeves or end caps.

Start your diagnosis by rechecking all the fastener torques on the Focus' front struts. The strut-to-knuckle bolt torque should be 67 ft.-lbs., while the mount-to-body nuts should be at 22 ft.-lbs. The strut rod can turn while you check for proper torque of the retaining nut, so hold it steady with a hex key while making sure the retaining nut is tightened to 49 ft.-lbs.

Loose or worn stabilizer links usually produce a rattling sound from the front suspension, especially over bumps. Try grabbing each link and shaking it up and down and inward and outward. If you feel looseness, retorque the retaining nuts to 36 ft.lbs. and repeat the exercise. If the play is still there, replace the stabilizer link(s) with an upgraded design (Part No. YS4Z-5K484-AA).

The rubber sleeves on the upper spring seats can also contribute to front end noise. If either sleeve is partially out of position, you'll get a creaking sound between the sleeve and the indent on the ridge of the upper seat. If the sleeve is worn or completely out of position, you'll likely hear a clicking noise, especially while turning. Install new rubber sleeves (Part No. 1S4Z-8484-AA) as required.

If the noise is limited to a popping sound from up top, Ford says the end caps at the top of the struts are probably worn. Remove and disassemble each strut and install new ends caps (Part No. 4S4Z-5L302-AA) then reassemble and reinstall each strut into the car, using the torque specs outlined above. Once you're done with the repairs, get to a parking lot and make a few slow turns to ensure that the noise has been eliminated.

Nissan

Interior water leak. Some 2004-08 Titan pickup trucks and Armada SUVs may leak water onto the carpeting after a car wash or heavy rain. Nissan says likely entry points for the water are small holes in the body seam sealer behind the dash and/or on the floor of the vehicle.

Start the diagnosis by grabbing a garden hose and squirting water under medium pressure at the junction where the windshield meets the cowl. Continue spritzing the area until the floor gets wet. Once it does, lift the carpeting and look for the leaky seam. Also check under the rubber mat covering the firewall, because there can be multiple leakage points.

Once you've nailed all the leaks, get a tube of 3M Fast 'n Firm Seam Sealer (3M Part No. 08505) and apply it to the body seam(s), allowing it to fully cure. To complete the repair, hit the windshield/cowl area with the hose once again to ensure that all the leaks have been plugged.

GM Truck

Coolant leak from rear. Some 2005-07 GM full-size SUVs with auxiliary heaters may leak quite a bit of coolant from the rear of the truck. One probable source of the leak, says GM, is a worn or compromised auxiliary heater hose quick-connect. The good news is that you won't have to replace the entire rear heater hose setup to stop the leak. The General now has a special repair kit (Part No. 19130031) to restore the quick-connect to like-new condition. Included in the kit are two O-rings, a retaining clip, a mid-spacer and full installation instructions.

Trucks that are susceptible to the coolant leakage and can benefit from the installation of the kit are Cadillac Escalades and Escalade ESVs, Chevy Suburbans and Tahoes and GMC Yukons.

Copyright Hearst Business Publishing Nov 2007
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