Maintenance Q&A
Older ECMs and winter’s toll on windshields

By Paul Abelson, senior technical editor

Q. I have a 1991 Freightliner FLD 120 with a 12.7-liter series 60 Detroit, with a DDEC 2 ECM. The company I am leased to had me install a Qualcomm 50 EOBR. The unit worked fine for a while. Then it stopped recording the mileage. The installer put in another new unit and the same thing happened. It worked, then stopped recording the mileage.

The installer says it’s my ECM and I should upgrade to a DDEC 3 or 4. Detroit Diesel says that won’t help. The problem is that Qualcomm has to install a truck-specific program.

Qualcomm says it’s the truck. I think the large trucking companies like the one I am with want to get rid of the old trucks. I have been with this company 13 plus years, and now they say fix it, get a new truck or get out. Please, can you help me?

A. I checked with my sources at Detroit Diesel. I’m afraid your installer is right. If you want to get an electronic onboard recorder (EOBR) or electronic logging device (ELD) to interface with your Qualcomm, you will need to upgrade to a DDEC 4. Earlier versions do not have enough memory or computing capabilities. Your 1991 FLD can, however, be upgraded to DDEC 4 capability. The cutoff is model-year 1990. Conversions are available from Detroit.

Reconditioned units are available on the Internet. I have seen prices ranging from $675 to $1,175. Installation and programming would be extra.

Electronic logs are not mandated by FMCSA. However, if your motor carrier insists on a logging device, there are units on the market that track hours-of-service compliance, but do not require interfacing with the ECM.

Although these may satisfy the need for an EOBR/ELD by your company, the company may have chosen an upgraded Qualcomm system for other driver communications. They may be using this as an opportunity to remove older trucks from the fleet, but that is beyond the scope of this column.

Q. I don’t know if it’s the shape of the windshield or what, but last year I traded my KW W900L for a T780. I love the new truck, but this winter I noticed the wiper blades started chattering, and this spring I can’t seem to get the bugs off. The fluid at the truck stop is useless. I even tried Coca Cola on one of those mesh-wrapped sponges and it helped a little. Any ideas?

A. Your older style two-piece, flat glass windshield was easier to keep clean because it was narrower than your new one, and easier to reach. But the main reason you and thousands of other drivers have had problems this spring is from the snow-removal chemicals so widely used this past winter. The chlorides leave a residue on the glass. That puts a drag on the wiper blade, causing the chatter. It’s the rubber dragging, then catching up with the blade assembly.

The situation was made worse this winter as many public works departments substituted sand and cinders to extend their short supplies of road salts. Those abrasive materials physically attack blade rubber. And in spring, tree sap causes wipers to grab and smear across the glass.

To thoroughly clean your windshield, you will need two different-color microfiber cloths (one for scrubbing and one for buffing) and a container of streak-free windshield cleaner made for vehicles. A household glass cleaner, even with ammonia, will not have the penetrating power to dissolve all that accumulates on a windshield.

Meguiar’s and Stoner Invisible Glass Cleaner are among those highly recommended, but there are other good ones, too. Products with ammonia, alcohol or detergents tend to leave streaks.

Fold each cloth in half and in half again. You should have hand-sized squares. Do not spray cleaner directly on the glass, especially the inside of the windshield. It could drip or be sprayed onto leather or plastic and could discolor the dashboard.

Apply the cleaner to one side of your folded cloth, lightly for inside glass and liberally for the outside. Do the inside first. When you look at the glass from the outside, you won’t have any misleading interior streaks or smears to confuse you.

Scrub the inside glass with the wet cloth, working in sections. As dirt becomes visible, fold the cloth to expose a new face, apply more cleaner and scrub another section of glass. When you are finished, don’t let the glass dry. Buff it with your clean, dry cloth to finish the drying process.

Before doing the outside, lift the wiper arms and keep them off the glass. You should change blades when done.

Buy clean new microfiber cloths for your windshield. Don’t use fabric softener to wash the cloths. Don’t use cloths that have been used to clean oily parts. No matter how much you wash them, they can still contain an oil residue.

The experts recommend against using paper towels or newspaper. They contain substances that will leave a residue that promotes streaking.

If you have a buildup of salts and chemicals, baked-on tree sap or road film, use a non-abrasive clay bar. Often used to clean up paint, this body finisher’s tool won’t scratch glass but will remove built-up contaminants.

When the windshield is perfectly clean, you can protect the surface with a polymer coating like Rain-X, or with a good-quality automotive wax. The coating will slow future buildups and make the windshield easier to maintain. LL


DO YOU HAVE A maintenance question?
Send your question to Paul Abelson, senior technical editor, in care of Land Line Magazine, PO Box 1000, Grain Valley, MO 64029; email them to or fax questions to 630-983-7678. Please mark your message Attention: Maintenance Q&A.

Although we won’t be able to publish an answer to all questions in Land Line, we will answer as many as possible.