Service slants

Motor, May 2000 by Juran, Ken

Ford

No temperature control. If you ever come across one of the mainstream cars or trucks listed below that seems to have lost its ability to control interior air temperature, check the blend air door actuator. Ford says its Manual and Electronic Automatic Temperature Control (EATC) systems use different actuators. They're even marked "MAN" and "EATC," respectively on a sticker. And just to make things more confusing, some 1998 actuators were updated from their 1997 counterparts in some vehicles.

The wrong actuator can cause blower speed control failure on Manual systems and no temperature control on both Manual and EATC systems. The electronic system can also set DTCs 24 and/or 25 as a result. To top it all off, Ford even admits that some of these vehicles may have experienced problems at very low mileage because the wrong blend air door actuator was installed at the factory. The vehicles involved are the 1997 Town Car and the 1991-98 Crown Victoria/Grand Marquis, Taurus/Sable/Continental and Explorer/Mountaineer.

Here's some help, in the form of the correct part numbers for each application. Match up the chart below to what's in the car and then set things straight by putting in the correct actua-- tor. (Note that the Engineering No. listed is what you'll find on the part itself; Ford never puts the part number on the item, only on the box.)

Dodge/Plymouth

Misfire DTCs with no symptoms.

The customer may describe this one as just an illuminated MIL on his 1997-99 Neon with the 2-liter SOHC or DOHC four-banger built before 11/3/98. If you find DTCs for misfire detection, just keep in mind that they may be real or fake. If you find DTCs for other problems, take care of those first. Then, find out if the customer has felt anything funny in the past. In some cases, there may be minor engine roughness after a cold start first thing in the morning that the customer conveniently doesn't mention. Also, the MIL may have turned on after that same cold start, or another.

If you find single- or multiple-cylinder misfire DTCs, follow through with a conventional misfire diagnosis to see what's up. If you come up empty, it probably means the DTCs were fake and the PCM needs reprogramming. Whether you or a dealer does the job, know for reference that Chrysler's MDS must be operating with Release 21 or higher and TIL CD Release 1175 or higher must be installed, in order to get the latest software update. Also, the repair needs to be described on an Authorized Software Update Label (Part No. 04669020) and attached to the PCM, and on an Authorized Modification Label (Part No. 04275086) and stuck underhood for future reference.

GM Truck

Brake pull and premature front pad wear. Brake pull or lead to either side, and premature front pad wear, can occur on some 1992-99 Chevy and GMC C/K Pickups, Cah Chassis and Crew Cabs with power brakes, some 1992-99 Chew and GMC C/K Suburbans with an 8600-pound GC\, and some 1996-99 Chevy and GMC fullsize G-vans with power brakes. General Motors says this is more common on trucks that have been used to tow a heavy load. The cause for all of it, however, is the choice of friction material used on the rear brake shoes. Installing realised rear linings, plus a different proportioning (combination) val\ve on the Suburbans only, should stop the front brake problems, according to GM.

The part number for the reused Dura Stop brake shoes is 18029651. The proportioning valve for 1992-94 Suburbans is Part No. 15650150 and for 1995 and newer Suburbans, Part No. 12548265.

Note that this fix doesn't apply to the 13XQ-inch brake shoe, the Dura Stop Part No. 18029650 brake shoe or any other size brake, according to GM.

Also, if you find the front disc brake pads extremely worn on the inboard side with veU, little wear on the outboard pads, check the clearance between the calipers and the steering knuckle bracket stops. GM stresses that you should measure the clearances individually and add them together for total clearance before removing the caliper!

If the total clearance to the knuckle stops is less dean .008 inch (20mm), file down the stops to achieve a total clearance of .010 to .024 inch .26 to .60mm). But whatever you do. don't Pale metal off the brake caliper.

Mercedes-Benz

Halogen/Xenon headlight repair kits. The current-generation E-Class cars ( 1996-present, and internally coded Model 210) with their four individual headlight lenses apparently have had some problems with premature bulb failure. So Mercedes-Benz has come up with two repair kits-one for halogen bulbs, the other for Xenon high-intensity discharge (HID) bulbs (the ones that burn so white they look blue). The halogen kit (Part No. 210 540 55 33) includes new parking light bobs and sockets, plus low-beam headlight bulbs. The Xenon kit (Part No. 210 540 56 33) comes with just the parking light bulbs and sockets. M-B says it's not necessary to replace the Xenon bulbs.

For cars with halogen headlights, replace both low-beam bulbs with a type H7L. The parking lights take H6WL bulbs. For cars built up to October 1997, install the new parking light sockets with the wiring harness. For cars built after October 1997, replace only the socket.