Getting your car ready for winter

Times have changed and so have the cars here are a few tips.

Rotating your tires is still a routine exercise but today your car may require the TPMS (Tire Pressure Monitoring System) to be retrained after you rotate the tires so that the dash reports the correct pressures and tire locations. Putting the system into training mode can be as easy as one GM system where having the key on and holding the lock and unlock buttons on your key fob until the horn sounds two times. Then you can first go to the left front tire and let out some air from the tire and the horn will beep one time. The horn beeps when the system receives the tire pressure sensors signal which goes into a fast update when the tire pressure changes rapidly. Continue the retraining by going around the car to the right front and repeat the step of letting some air out, then onto the right rear tire and finally the left rear tire. When the last tire is trained the horn will beep twice again instead of just once.  If you only get one beep at each wheel you may have to access the spare tire as well. The last step is to then reset all of your tires to the proper specification which will be on a label on the driver’s door or its frame. This was just one example, there are a lot of different systems out there so consult service information or your local shop for your model.

Time to change your oil?

There was a time that the only thing you needed to know was the SAE grade and to look for the API and ILSAC ratings. Today even the simple oil change is much more complicated. Specifications like GM’s dexos1, Chrysler’s MS6395R, Ford’s WSS-M2C930-A all greatly exceed the current API SN and ILSAC GF5 ratings. The engine oil life monitor systems on today’s cars countdown start-ups, mileage driven, temperature conditions and will alert the driver once it’s time to have the oil and filter changed. While conventional oils may last the 6000 miles that Honda and other Asian manufacturers require, they often do not last long enough for Ford and GM vehicles which can call for serices to be done in the 7000 to 10,000 mile range while a manufacturer like BMW may reach 15000 miles.

Is it time to replace your battery?

For many people replacing a battery when it gets to be five years old is simply about buying the peace of mind that they know the car will start once the bad weather really hits. For others they will make that battery to go until they know that it needs to be replaced. Either way there is more to it than just dropping in a new one. One step is to attach a memory minder so that the car doesn’t get completely depowered while the battery is replaced. That’s pretty convenient for not needing to reset your clock and the radio stations but it also keeps the other memories on important computer systems from being cleared which can have some unpleasant surprises. Another important issue is today the charging systems are computer controlled and it has been adjusting to that older battery and that will cause it to charge the new one incorrectly if that isn’t reset. Many techs associate that with manufacturers like BMW, when in fact just about every manufacturer has this function. Once again consult service information for specific details about your car.

Engine Coolant, Antifreeze

Beware of claims of universal antifreeze, there is no one size fits all specification. Some manufacturers require silicates, while others ban them. The same goes for phosphates, and borates which are all good for some things that may be used in a car’s cooling system and can be bad for others. When you go to the parts store to buy new antifreeze consider buying it pre-mixed where you don’t add water. That saves you an important step that most don’t realize. Antifreeze isn’t designed to be used with tap water, if you buy concentrate you are supposed to mix it with distilled water.

Did your doors freeze and get stuck closed last year?

A little silicone spray on the rubber door seals will displace the moisture that can freeze and make it difficult to open the door in the morning.

Do you need to use dry gas or injector cleaner?

Gasoline today is up to 10% ethanol which is an alcohol. “Dry gas” is normally isopropyl alcohol, and a common property of each is they like to be in solution with water more than they do gasoline. Dry gas never took water out of fuel, it simply helps prevent any water in the system from freezing, so no,  you really shouldn’t need to use a dry gas additive anymore  but injector cleaner is different. Using an extra injector cleaner additive can help keep your car running better and a good rule of thumb is use it once a year or every 25,000 miles. Manufactures like GM recommend Chevron Techron especially if you normally don’t purchase a Top Tier fuel. That’s a subject you should Google, Top Tier Fuel, there is a difference in gasolines that you can run in your car.  

 

Not Ready For Testing

Not Ready For Testing.

This is a common problem that we deal with a couple times each week ,  usually the story goes something like this.

The car was due for inspection and the check engine light was on so it failed the emissions test. During the course of the repairs the codes get cleared and then the owner is told that they have to drive the vehicle for a while to try and get the car ready for its emissions test but it keeps coming up not ready. 

The OBDII emissions test is really carried out by the car every time that it is driven, all the states emission test does is collect the cars data as it reports if it passes or fails. When someone clears the codes they also clear all of the test results that make up the monitors that the state needs to see completed in order to know if the car is operating correctly or not. If all of the tests that make up a given monitor didn’t get to complete, then that monitor won’t be set to ready. When we have to deal with one of these situations, understanding what it takes to get given tests to run is very important because tests can be stopped from running because of the car’s operating environment failing to meet certain minimum criteria. One example of that could be if the ambient temperature was too low or too high or if the engine coolant temperature did not stay within the programming limits. Both of those would be considered blocking conditions where the tests are prevented from running because the results would be too unpredictable. There are other times where the vehicle might not have been driven long enough to ensure full system operating temperatures. Some of those aren’t even directly measured but are inferred by operating conditions such as the catalytic convertor temperature. The engineers use modeling to try and predict how hot the catalyst would be based on the way the vehicle was driven, then with a catalyst at that temperature, they measure the oxygen storage capability of the catalyst and write the testing tables for the vehicle’s computer to run.

Once we have confirmed that no blocking conditions are occurring, we then have to make sure that each test enable criteria is met. This is easy to do in some cases with a scripted drive cycle that most manufacturers publish, or it can be done with a scan tool as in Chrysler’s case where the scan tool displays the parameter limits and the vehicle just has to be driven within them for a period of time.

If a test fails and it’s a two trip test, you will find a trouble code but it is set in global mode seven and those are known as pending codes.  They have to fail twice in a row to turn into a confirmed code and cause the check engine light to come on.

2002 Rendevous won't shift

This vehicle just had a used transmission installed and it wont shift correctly. When in drive it starts out in third gear, and once up to about 30mph it shifts into second. Then at forty it shifts to third for a few seconds and then goes into limp in mode, which is back to second gear. Reverse operates normally. Typically the limp in or failsafe modes for an electronically controlled transmission will give you one forward gear, which is what ever gear both shift solenoids turned on creates, and you will have reverse, neutral and park. All of these are commanded by the manual valve which is directly linked to the shifter cable. The computer in the car was setting a P1875 for the pressure control solenoid circuit open.

To test for the cause of that code, the technician needs to access the PCM which is inside the air cleaner housing. On connector #2 pins 44 light blue / white, and 45 red / black provide the feed power to the solenoid and the ground return to the PCM. By unplugging the connector at the PCM the resistance of the circuit can be measured and the circuit was open. The next step is to find out where and why the circuit is open and then plan to do the repair. One of the easiest things to do is to remove the connector at the transmission and jumper the two pins together and then ground one at the PCM connector and provide power through a small lamp. In this case something that draws 1.5 to 2 amps such as a brake lamp bulb. The lamp lit up confirming that the wiring was OK, and that means that the problem is inside the transmission or with the connector itself.


The following two pictures are screen shots captured with my bore scope.

The red arrows point out the damaged pins, note the second one on the top, right hand row and the fourth one are pushed out of place, while the third is bent up out of line.

Most of the time when a connector is damaged like this it isn't a big deal to disassemble and repair it. Unfortunately with the way this connector for the transmission harness is assembled, that's going to mean that the transmission will have to come apart to access the other side of the connector.