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Automotive Industry

Service slants

Motor, May 2003 by Savasta, Bob

Cadillac

MIL and/or ABS light illuminated, multiple DTCs set. Eventually you may get a 2003 DeVille in your shop with the MIL and/or ABS light illuminated and DTCs P0340, P0341, P0410, P0502 or P0503 stored in computer memory. The owner may also complain of erratic speedometer operation or sloppy transmission shifting. According to Cadillac, all of these ailments could be due to the radiator surge tank outlet hose clamp tabs digging into the main engine harness, creating shorts in the various circuits within the harness.

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To check things out, head for the rear valve cover and look for the aforementioned metal clamp, located just above the cam sensor. If its tabs have indeed penetrated the harness, slide the clamp up and repair the damaged wiring, making sure you seal everything up with electrical tape. When resecuring the clamp to the hose, rotate it 90[degrees] counterclockwise so that its tabs are pointing upward (see illustration), to prevent a reoccurrence of the problem.

Chrysler

Engine growl. A low-pitched growl coming from the engine bay of a 1998-2000 LH-car (Concorde, Intrepid, LHS, 300M) with a 2.7, 3.2 or 3.5L V6 could be nothing more than belt slip-page at the alternator or power steering pump. Chrysler says the noise is most prevalent following a cold start, and occurs in Drive or Reverse with the engine at 1000 to 1300 rpm.

To zero in on the diagnosis, let the engine sit overnight. The following morning start it up, place one foot on the brake, shift into gear and tip the throttle until the rpm is in the range indicated above. If the growl becomes obvious, shut the engine down and get out a belt tension gauge. Position the gauge on the belt midway between the pulleys and take a reading. Belt tension should be a minimum of 120 pounds. If it isn't, loosen the idler pulley mounting nut a half-turn, then turn the adjusting screw clockwise until belt tension sets up between 120 and 140 pounds. Once there, tighten the idler's mounting nut to 40 ft-1b and recheck belt tension with the gauge.

Ford

Spark knock. According to Ford, some 1998-99 49-state Crown Victorias and Grand Marquis may exhibit spark knock while accelerating in temperatures above 90[degrees]F. The cause could be improper electric cooling fan operation, too much spark advance commanded by the PCM or the wrong base ignition timing.

Begin the repair by performing normal engine diagnostics, pulling and addressing all DTCs, as required. Next, attach your NGS (or similar scan tool with bidirectional capability) to the underdash OBD II connector. Select "Output Test," then activate the low-speed fan, followed by the high-speed fan. If either fan fails to respond, repair problems in the circuit, then test-drive the vehicle to see if the spark knock condition has been eliminated.

If it hasn't, reprogram the PCM using the NGS or WDS and the following calibrations: For tear tags FJB1 and FJB2, use NGS/WDS qualifier 9VNA-AK; for tear tags JCA1 and JCA2, use qualifier 9VNA-AL; for tear tags VTCD and VWNO, use qualifier 8-18F; finally, for tear tags XDXO and KCLO, use qualifier 8-18H.

When the PCM reprogramming has been completed, once again take the vehicle on the road to see if the spark knock condition is gone. If it isn't, you're going to have to retard the base timing by performing a software octane adjustment procedure. Caution: Make sure you adjust the base timing and not the octane rating during this critical step. The procedure can be performed only once and is not reversible!

To begin the adjustment procedure, you'll need an NGS or WDS hooked up to the DLC, the latest service card and flash cable and a fully charged battery. Next, turn the ignition to ON, install the service card into the tester and select "PCM Programming" from the menu. Continue by entering any eight numbers of your choosing, then select "Trigger." Hook up the flash cable, cycle the key off, then on, then select "Trigger" once again. When prompted, select "Yes" to display the latest calibration, then "Yes" again to modify the PCM parameters. Select "Octane Adjust," then scroll the thumbwheel on the tester until "Retard" is highlighted. Finally, select "Start" to activate the octane (base timing) adjustment. If these procedures are completed properly, the tester should inform you that a successful PCM update has been achieved.

Toyota

Rear suspension noise. A 1994 Corolla that produces a groaning or squeaking sound from the rear of the vehicle probably needs updated stabilizer bar bushings. The part numbers are 48818-12150 for Japanese-built vehicles and 48818-02021 for U.S.-built cars. When doing the job, Toyota recommends pulling the rear strut rods and applying lithium- or silicone-based grease to the outer bushing ends.

GM Truck Engine rattle. Some 1992-2002 C/K-, S/T-, M/L-, G-and P-trucks with the 4.3L V6 (VINs W and X) may give off a rattling noise at 2000 to 2500 rpm under moderate to heavy loading. According to the General, this noise is due to the "natural loading and unloading of the balance shaft and gear drive assembly," and does not represent any significant durability risk to either the engine or its components. GM cautions that attempting to alleviate the noise by replacing the cam drive or balance shaft parts will probably prove fruitless (not to mention expensive), and recommends following normal diagnostics to rule out more common problems that can mimic the noise, such as detonation, piston rattle and crankshaft and main bearing knock.

Automotive Industry

Service slants

Motor, May 2003 by Savasta, Bob

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