Common principles of diagnostic with FORScan

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Common principles of diagnostic with FORScan

Post by FORScan »

In contrast to majority of OBDII applications, FORScan is designed to use service level abilities, like a professional equipment. It means that FORScan operator must have at least some basic knowledge of troubleshooting principles in order to use it effectively. This article is written for people that have no these skills yet but looking for a start point.

In simple case, the troubleshooting sequence is:

Step 1. Connect to vehicle
Step 2. Check for diagnostic trouble codes (DTC). If there is no any code related to the problem, go to Step 6.
Step 3. Analyze the DTC code(s) found.
If the DTC description provided by FORScan doesn’t contain enough information, go to Step 5.
Step 4. Fix the problem. End.
Step 5. Obtain additional information using FORScan datalogger (read PIDs). If information is enough, go to Step 4.
Step 6. Try to get more information using a workshop manual for the vehicle, if it is available. The workshop manual may contain a lot of helpful information, including pinpoint tests and diagnostic charts.
Step 7. Try to learn other users’ experience (can be found using Google by DTC or problem description).

As you may see, read and analysis of diagnostic trouble codes is the first thing that has to be done. So it is important to understand what DTC is and how it works. Generally speaking, if a module finds an issue, it throws a diagnostic trouble code so a technician can read it and realize the issue exists. The priority of the issue may vary in range from not really important (rather some kind of warning) to crucial. In the last case the module lights its malfunction indicator lamp (MIL) up so the issue becomes visible for the driver. Otherwise, if the issue is not important enough, the driver will not see it until next visit to a workshop.

In Ford/Mazda diagnostic, there are 2 kind of codes: Continuous Monitoring (CM) and On Demand (OD). CM codes are thrown by a module if it detects an issue during its regular work . Operator doesn’t need to perform any action to generate these codes, but just read them from the module memory. OD codes are generated during a self-test (on demand test) called by operator. Self-test/OD codes are helpful in case of malfunction that cannot be detected without operator’s assistance. For example, BCM/GEM module usually has no ability to detect door ajar switch malfunction as when the door is closed, the switch circuit is normally broken. So the module cannot recognize if the door is closed, or the switch is damaged. In order to find this out, operator has to run the module self-test with all doors opened. If any switch is broken, the corresponding OD code will be thrown.

Format and information, provided in DTC, depends on module. We conditionally divide the ECUs into 3 groups:
- App. 1994-2003 – provide no malfunction sub-code and status info (except standard OBDII codes that may have Confirmed or Pending status). Instead of, the DTC descriptions usually pretty detailed and informative.
- App. 2004-2008 – provide minimum of sub-code and status info, but also quite detailed description.
- App. 2009-now – provide informative sub-code and status code, but usually very short description, as designed to be used in conjunction with technical database that explains the issue (workshop manual, Ford ETIS etc).

Let’s review a real example of diagnostic session:

Ford Ecosport Europe 2014, less than 2 years old, 11700 km. Unstable start of engine(after 2-3 attempts). ABS, TCM, EPS malfunction lamps light up right after the start and SYNC asks to visit a workshop urgently. Car owner is in panic. After connecting FORScan a lot of diagnostic trouble codes were read. Although this may look like a serious global trouble, or even multiple troubles, brief analysis shows that almost all of these codes indicate low/unstable power voltage:
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Considering that multiple modules report approximately the same, the only explanation is that the battery died. To confirm, read VPWR PID in PCM module in KOEO and KOER mode. It shows 10.5 in KOEO mode (that’s too low – should be around 12) and 14.5 in KOER mode (that’s normal and means the alternator/charging are most likely fine)

So our conclusion was that the battery is dead (bank short circuit).

Interesting thing is that this car didn’t show typical signs of dead battery – starter worked and engine ran even at very low voltage, just a bit slower than usually. When the voltage fell below some threshold, starter was simply blocked. The car owner can’t believe the brand new firm Ford battery died for less than 2 years of accurate use, so he decided to visit a dealership in hope it will be resolved in bounds of warranty. Unfortunately, he was wrong – dealer’s diagnosis was the same: battery died because of constant undercharging (caused by small mileage - work in permantent start-stop city conditions) , not covered by warranty. So the owner had to pay not only for the new battery, but also for the dealership diagnostics.

Finally, 2 more screenshots that illustrate what are the sub-code (Additional Fault Symptom) and Status and how FORScan displays them:
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5.jpg (104.65 KiB) Viewed 111313 times
Posts: 14
Joined: Tue Jan 07, 2020 4:29 am
Vehicle: Ford F150 4x4 xlt 3.7L 6 cyl 2014

Re: Common principles of diagnostic with FORScan

Post by Clyde »

Thank you for posting this information! I am a brand new beginning user of Forscan brought to the program through research in looking for solutions for programming key fob for my truck and have been amazed at all of the functionality of this program!
Amazed and more than a little intimidated by it since I would hate to cause myself more headaches and bigger repair bills should I make a mistake.
Posts: 1
Joined: Wed Sep 09, 2020 12:32 pm
Vehicle: 2017 Ford Ranger 2.2 (150PS)

Re: Common principles of diagnostic with FORScan

Post by FranTheMan »

Good information and a great base for noobs.
Posts: 1
Joined: Sat Aug 29, 2020 6:08 am
Vehicle: Ford Falcon AU series 2 Ute-2001-Dedicated LPG-143

Re: Common principles of diagnostic with FORScan

Post by Boof »

Should have read this properly the first time. It would have saved me a few thinkaches :shock:
Posts: 1
Joined: Wed Nov 04, 2020 2:05 pm
Vehicle: Ford F-350 Superduty 6.2 Gas 2013

Re: Common principles of diagnostic with FORScan

Post by Mayrin01 »

Gracias por la informacion. Estoy en Venezuela y tenia dudas si el programa funcionaba con vehiculos fabricados en mi pais. Acabo de instalarlo en mi computadora y adquiri el ODBLINK EX y ya lo estrene con mi camion Ford F-350 Superduty 6.2 del año 2013 y estoy viendo codigos que mis otros dos escaner no monitoreaban(Foxwell y Blue Driver). Con la informacion publicada en este apartado podre comprender mejor las fallas que mi camion esta presentando. Muchisimas gracias.
Posts: 136
Joined: Sun Aug 16, 2020 1:10 am
Vehicle: 2013 F150STX 4x4 5.0

Re: Common principles of diagnostic with FORScan

Post by rbentnail »

This site -> can help determine what the codes mean.
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Joined: Sun Jan 31, 2021 12:45 am
Vehicle: Escape 2.0L EcoBoost 2015

Re: Common principles of diagnostic with FORScan

Post by DGeorge747 »

I just used FORScan for the first time on my 2015 Escape last night. I didn't make any changes and was just looking at the information provided and it's abilities. It seemed to work great.

Then I started to get errors on the car's dash screens, the LEDs on the front of the car started flashing and the driver's side LED stayed on for awhile. I could hear what sounded like various relays clicking and could not start the car. It seemed that the car was completely dead other than some small movement in the hands of various gauges.

I checked the voltage on the battery which was only about 6 volts. I attached a battery charger and left it charge over night.

This morning the car started and ran fine, although I didn't drive it.

Should a battery charger be connected to the battery every time FORScan is used? Or do I have a week battery? This car is driven everyday, so it doesn't sit for long, and we have not had any problems with it.

If a battery charger is to be used each time FORScan is used, will FORScan ever be able to diagnose a battery, alternator or voltage issue,because of the battery charger continually inputting voltage into the system ?

Thank you to anyone who may be able to answer my questions and help me better understand how to use FORScan and it's many abilities.
Posts: 1
Joined: Sat Mar 21, 2020 6:23 am
Vehicle: Ford F-150 2.7l 2020

Re: Common principles of diagnostic with FORScan

Post by bjw »

I am not a pro, hopefully more people will reply, but I have used FORScan quite a bit with my F150 and never experienced anything like that. I cannot imagine how that much power could be removed from the battery in the time you were connected without something getting really, really hot. Good luck, please let us know what you learn-
Posts: 7
Joined: Sat Jan 30, 2021 9:53 pm
Vehicle: Ford Focus, 2.0 Flex Fuel, 160 HP, 2013

Re: Common principles of diagnostic with FORScan

Post by Minstafl »

it's been a while since used mine. but I think I'm remembering the self check tests that forscan runs on diagnostic check up, to look for problems if any. Some with key on engine not running, then with engine running. Maybe the key on engine off diagnostics test was enough to knock down a weak battery, so consider the age of the battery, is it a 2, or 5 year, etc. Maybe check battery voltage before and after the key on engine off testing.I had to get a new battery for 2 vehicles I've used forscan on before doing any testing, as they were both beyond recharging from lack of usage prior to repair. Which I did read that that wouldn't have been your issue, but maybe just nearing it's end of service.
Posts: 7
Joined: Sat Jan 30, 2021 9:53 pm
Vehicle: Ford Focus, 2.0 Flex Fuel, 160 HP, 2013

Re: Common principles of diagnostic with FORScan

Post by Minstafl »

In realation to :

If a battery charger is to be used each time FORScan is used, will FORScan ever be able to diagnose a battery, alternator or voltage issue,because of the battery charger continually inputting voltage into the system ?

Most chargers on the market today are going to have, for lack of a better term, smart sensors to only charge the battery as needed. And chargers only charge the battery, nothing other than that. Also, the vehicle is made so that it monitors system voltage continuously, (so the system is designed to handle the flowing voltage, where ever it needs to go), as in does the battery need to be charged after leaving the headlights on accidently, (by way of the alternator, not a battery charger). Whether after being jump started, or if there was sufficient volatge to still start the car, etc. Would I run the diagnostics key on engine not running, with the battery charger connected, that one I'm not sure about, so I probably wouldn't. And finally, for the last part of your entry. Forscan is a, among some other things, a scanner to read engine trouble codes. Which includes the charging system. So that if you have low voltage enough to throw a code, then forscan will tell you what caused the code to set. I can't say how much in depth, as I've not ever used a scanner to troubleshoot a charging problem or weak battery, One of the things my favorite car parts store does for free, checking the charging system and battery life. I forgot to mention earlier. The flashing lights and other things going on on the dashboard, relays clicking, may have been, emphasis on 'may have been', forscan running through the self diagnostic.
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