G&G Pops the Hood Part 2

In part 1 of this series we got the hood open and secured. 

Depending on your car, there are a lot of things to take in. Look around a bit. You can't spot something wrong until you've learned what right looks like. Hopefully by the end of this series you'll be so familiar with your under hood inspection that any problem will be obvious. 

Now we have to start somewhere. Checking oil level is a good place to start. A LOT of cars in the shop these days are low of oil. I know from talking to customers that some don't realize a car can need oil added even when it isn't time for an oil change. Usually the oil level stick isn't too difficult to find. Some are marked, some aren't. 

Ideally your car should have been sitting long enough the engine is cool and the oil has drained back into the oil pan. When the engine is running oil is being pumped to the various areas it is needed. After the engine is shut off it takes a minute or so to drain back to the crankcase. The oil level stick reaches down into the oil and has markings to indicate how much oil is in the pan. When you have identified your oil stick, grasp the handle and pull straight out. Plastic handles have been known to break so don't be over aggressive. Once you have the stick out and in your hand you should see oil on the lower end. Note the condition of the oil. If the oil is terribly dirty you probably need an oil change. Discolored and thick like milkshake could mean coolant is getting into the oil. If the oil doesn't look normal to you then you should let someone more knowledgeable take a look. For our purposes here though we'll continue with how to check the oil level. Wipe the oil off of the stick. There will be a full mark and a one quart low. Insert the cleaned stick fully into place then remove to see where the oil level is on the indicator. The truck below had an oil change a few weeks ago. The clean oil is hard to see in the picture but shows a slight overfill just at the last L in full. About a half quart over. 

Let's try another. The oil condition looks good in this one and it is about half a quart low. Don't add a half quart. Just remember to check later on. Some cars can burn a half quart or so quickly but take a long time to need a full quart. If you try keeping it topped off you would be constantly adding oil to a car that would be fine if left alone.

If you do need to add oil use the manufacturers recommended oil as outlined in your owners manual. Add oil as needed by removing the oil filler cap. A funnel can help prevent spilling to the exterior.

Stay tuned for part 3!

Kenneth Hayes

G&G Auto Repair

G&G Pops the Hood Part 1

Not many people take a look under the hood these days. That seems odd to me since I was taught to keep an eye on fluid levels and check for obvious problems.  I know cars are generally more dependable and longer lasting now but if you run that car out of oil or coolant you will still end up with a major repair problem. I want you to know your way around your car. Let's start with opening the hood.

Most cars have a hood release under the dash that you pull to release the hood latch. 

When you pull the release you are pulling a cable attached to the hood latch. The cable pulls the latch release and a loaded hood spring can then let the hood pop up. 

If the hood release doesn't work as described you probably need some lubrication of the latch. Bump the hood with your hand and/or just grab under the front and pull up. 

Once released, the hood should spring up enough to engage the safety catch. The safety catch is usually a hook that must be released before the hood will open fully.

You may need to both feel and look for the release to see how it works on your car but it isn't usually difficult. Once you have the hood open you need hood support. There are various types of hood support but all are there to keep the hood from crashing back down when you let go after raising it. 

There are hood support rods on some cars. Basically metal rods that prop the hood up. 

Some people choose a custom design.

There are hydraulic supports.

If your hood uses these and you don't feel them helping to raise the hood they need replaced. Or, use the custom broom handle method. 

Kenneth Hayes

G&G Auto Repair

Why is this truck stalling?

03 Chevrolet Silverado Z71 LS 5.3

The complaint is the engine dies (stalls) after the battery failed and after battery replacement. 

The first thing comes to my mind is an idle control problem. The trucks engine computer has been adapting programming as needed to compensate for wear and age conditions. When the battery power is lost so is the adaptive programming. Commonly the throttle bore and plate have been building over time a layer of carbon. Because this happened slowly the computer was able to make changes in idle control strategy and maintain idle. The loss of battery power reverted the system back to factory settings and since there was no carbon then, the settings aren't correct for maintaining idle now. If this is the problem then I should see the stalling being related to a slow idle speed and a slow response to an rpm drop at idle. 

You can see the idle drop to a near stall in this pic when I place the shifter from park to reverse. The iac counts are a rough indicator of how hard the iac is working to maintain idle speed. You can see iac is slow to respond to the rpm drop. So there is probably a carbon problem.

You have to get in there with a rag and some cleaner. Hold the throttle plate open and wipe the area clean.

Now after reassembly we start the engine to clear any excess cleaner and let the idle stabilize. Look now how quickly the iac responds and how easily it maintains idle rpm as I move the shifter this time.

A test of alternator and battery draw and this truck is fixed.

Kenneth Hayes

G&G Auto Repair

Testing Battery Drain 3

Hmm. It looks like battery drain is going to be a common subject on this blog. The most recent was an '03 Dodge Ram 1500 with a complaint of battery going dead after sitting. The customer had spent several dollars trying to get a fix at other shops but still had the problem. Now the truck came in on a tow because the battery was dead and wouldn't start with a jump. I used the jump box and got the engine cranked to get the truck into a work bay. I didn't need to use the memory saver because the battery was already dead. I just disconnected the battery cables for a quick battery test. The battery tested bad so I installed a known good battery to use while checking the electrical system. I put the original battery on a slow charge. I would re-test it after it was fully charged.

With the good battery on the truck and after giving it time to "timeout" the modules, I checked the actual battery draw which was well within specs. So there was no excessive drain on the battery at this time. 

I had to halt testing at this point after I was rudely interrupted by quitting time and my stomach growling...

After an overnight on the charger, the battery was 100% charged and I installed it on the truck after removing my known good test battery. I gave the truck several starts while running accessories to get rid of surface charge. This battery still tested bad. I removed the bad battery and re-installed my known good battery because before I called the customer with a report I still needed to test the charging system. The idle rpms were very erratic on the truck so my voltmeter was dancing quite a bit. I could see I had alternator output but I needed to fix the idle problem. 

I should explain something. The engine computer has a learned memory that can be cleared with a loss of battery power. One of the typical things the computer has adapted to is throttle plate coking or buildup of carbon at the throttle. As the dirt/carbon/crud built up at the throttle the engine computer made changes to its idle strategy and those changes became learned programming. Loss of the battery power here cleared the learned memory so that when I started the truck it fell back to the original idle strategy and not an adapted one. In other words, it idled poorly now because it wasn't compensating for the dirty throttle bore. I could either let the truck run and operate long enough to relearn idle or, since the problem was a dirty throttle, clean the throttle. I usually choose to clean the throttle. I was right about the throttle I see. 

After cleaning the bore and plate the idle was steady and the voltmeter showed a good alternator output. 

In the meantime the customer had picked up his original (bad) battery and taken it to the store he purchased it from a year ago for an exchange. After doing the cleaning and idle repair with my battery installed I didn't want to chance losing what I had gained with another memory dump so I connected a memory saver while making the swap back to his new battery. 

I think I've covered it all. Good fix!

That's the magic. 

Kenneth Hayes

G&G Auto Repair

TPS code 22

Today is a '92 Chevy K2500 6.5 diesel with a complaint of a TPS fault code that won't go away. The TPS (throttle position sensor) has been replaced but the code remains.
Ideally what I would like to see is the code number and scan tool data that would show me what the engine computer is reading as TPS voltage. I do have scan tools that read these older GM systems but when I tried the OTC Genisys with the Pathfinder attachment there was no 6.5 diesel under engine options. Ok, I have an AutoXray tool. No communication. OTC Monitor 4000 Enhanced, remember those? Uh.. no. I have attachments for the Solus Pro for GM but maybe I should just read the codes as this scan attempt is turning into a time consumer. Now if you want to read the codes on one of these using primitive tools, you can. You need a working SES (service engine soon) light so turn the key and see that it does come on.

Turn the key off. Find your diagnostic connector under the dash. (Not a good shot.)

I'm gonna share a tip here that you might need to know some day, or maybe never, but it's a good tip anyway. If you look closely at this diagnostic connector you can see there are small "ears" sticking out from each corner at the bottom making it wider at the bottom than at the top. Those ears are the bottom of the connector no matter how it is positioned in the car. If you are working on a car and find that connector turned upside down from this picture, or turned sideways in either direction it doesn't matter. That widest part is still the bottom of the connector. The reason that is important is that to trigger the SES light to flash trouble codes you have to jumper those two terminals on the upper right of the connector. You can't tell where the upper right is if you don't know where the bottom is. You can use a wire or I'm going to use a paper clip. Jumper the two connectors at the upper right.

Once you get the jumper in place, get in a position to turn on the key and watch the SES light. The light should begin flashing when you turn the key to the on position. Don't start the truck. Just turn on the key and watch the flashes. You may need to make a note of the codes if there are several. On this truck the light should flash a 12 initially. That is one long flash, pause, two short flashes. The code will be repeated three times. 12, 12, 12 long pause and then next code if any. In this case the only code output other than 12 was 22. Turn your key back to off and remove your jumper.
Now the short description for a 22 is probably going to be something like throttle position sensor voltage low. There is a school of thought that you'll come across that believes a sensor code means you need a sensor. It's wrong. What the code 22 is saying here is that the engine computer isn't seeing a voltage signal from the TPS. Sure that could be a bad sensor but it could also be many other things and no diagnostics have been done by reading a code. It's the first step, not the journey.
The next step is to inspect. The sensor is obviously new and the connector looks ok.
This sensor has three wires. It needs a ground on the black wire, a reference voltage on the gray wire, and the blue wire carries the voltage signal to the engine computer. Since the code is saying there is no voltage on the blue wire, I'll start with that. Connect a meter to measure voltage on the blue wire and turn on the key. The code isn't misleading at all. There is low voltage on the blue wire.

What I need to know next is if I have a reference voltage and ground going to the sensor. If the ground and reference circuits are good then I can connect the meter between the two wires and see reference voltage when I turn on the key. Disconnect the TPS and connect the meter leads to the black and gray wires on the engine side of the harness, turn the key on.

The five volt reference voltage is there. Since I'm measuring between the sensor ground and reference wires at the connector then I know the sensor is getting what it needs from the engine harness. Let's go back to the blue wire. The blue is the actual signal from the sensor to the engine computer. I measured before and saw no voltage on the signal wire. This time I'll measure the voltage on the wire while accelerating by just manually pushing the throttle shaft open.

As I open the throttle, the sensor signal voltage rises from 0 to 4 volts. The sensor does work. So why do I have a code 22? A code 22 will set when the TPS signal voltage drops below .06 volts. It does that each time the throttle is closed so that sets the code. At closed throttle the sensor reading should be .5 volts. The sensor is slotted and is adjustable. This could be a matter of the sensor not being adjusted when installed. I'm going to monitor the voltage signal, loosen the mounting screws and see if I can get .5 volts at closed throttle by adjusting the sensor.

Success! What I'm going to do now is disconnect the battery to allow the code to clear from memory. Don't do this on most cars and only for a reason on those you do. On this model that is how the codes are cleared and not with a scan tool. I'll give it a test drive and then another check of codes to see if the 22, or anything else, returns.  

All good! That's the magic!

Kenneth Hayes

G&G Auto Repair

Testing Battery Drain 2

This '99 E350 Ford sits a lot but the customer says he has to boost the battery too often. The van starts fine with a jump start so he does that and brings it in to my shop. The battery is dated November '14.
The van starts fine with no boost needed in the parking lot so the battery is not dead at this time. I want to verify we have a good battery so a battery test is needed. I've mentioned before I like to use the tester that measures internal plate resistance so I need to disconnect the battery cables at the posts. Since this battery is not dead the KAM Keep Alive Memory or the engine computer's learned memory should be saved. If I disconnect the cables the KAM will be cleared so I'll connect a memory saver to the diagnostic connector. These devices keep the engine computer powered while the battery is disconnected.

This battery tests good but is only at 70% charge. I know the battery was discharged and jumped so it hasn't been fully charged. I'll need to put the battery on the charger.

Getting a full charge can take several hours so I'll install a known good battery from my stock and continue testing while the battery comes up. After the new battery is connected I can disconnect the memory saver.

After allowing for the modules to time out I check battery draw, which is within specs.

I need to test the alternator. I put the voltmeter on the battery and measure battery voltage before starting the engine. I'll compare that reading to the one I get with the engine running.

I like to use a simple voltmeter initially and only go further when I see a reason for more testing. Here I see a need for more testing. I notice the meter is showing a charge and is in the "ok" zone but not by much. There is no load on the system and the engine is at idle. That's not looking like a good alternator output. I turn the lights on and the alternator isn't keeping up. I'd like to rev the engine and watch the meter but I can't do that from under the hood on this van.

I need deeper testing and I need to be in the driver's seat where I can rev the engine as needed. I have a tool perfect for the situation. A wireless tester that connects to the battery yet lets me use a wire free remote to see what's going on while I'm in the driver seat. This alternator is bad.

I replaced the alternator and did another test with the voltmeter and with the tester.

After a few hours the battery is fully charged.

I again use the memory saver re-install the original battery. I turn the headlights on and crank the engine a few times to get rid of the surface charge, then its time to disconnect the battery for testing.
The battery tests good. The alternator tests good. The magic is done.

Kenneth Hayes
G&G Auto Repair