1. Sherlock Holmes Diagnosis NACAT July, 2010
Jim Morton
Jim Halderman

2. Introductions Jim Morton-(aka Sherlock Holmes)
Jim Halderman-(aka Mr. Watson)

3. Topics to be Discussed Teaching the diagnostic process
Interviewing the customer
Interviewing the vehicle
Interviewing the vehicle history
The repeatable diagnostic procedure
Tips and tricks

4. Teach Diagnosis? Do you teach a diagnosis procedure?
If so, in which course?
All of them?
We both teach diagnosis in all courses
It helps make the subject “real world” 4

5. Here is What We Hear
We get asked for help after they have tried EVERYTHING
What we usually find is that they had no real direction or approach
Is this happening to you too?

6. Isn’t this what is important?
We all teach how to perform tests such as a compression test
Is a compression test the first test that should be performed for a driveability problem?
Not so much how to test, but a TRUE
game plan on each driveability concern

7. General Tests
Decide what GENERAL test would eliminate some of the possible causes
In most cases we have the problem nailed after 3 general tests to the right circuit or component

8. Pinpoint tests
We then decide what Pinpoint test to perform to find the root cause

9. The Old Days
My father opened the hood and felt the movement or play in the cooling fan
Sir, you need a water pump 9

10. How Does it Work Today?
We have to go through a diagnostic procedure to determine the root cause of the concern
Then isolate the circuit or part and perform a pinpoint test to determine the root cause
It is easy Mr. Watson if you ask the right questions 10

11. “The” Plan 8 steps Easy to remember Repeated the same way each time
Has to be continuously repeated to students otherwise they tend to forget it

12. Like Peeling an Onion
Get to the heart (root cause) of the problem requires some peeling and a plan of action

13. Finding the “ROOT CAUSE”
In my mobile diagnostic business, a VERY normal statement is made to me “The SAME component keeps failing”
An example of this would be 3 electric fuel pumps in 2 years replaced on the same vehicle

15. First Step Verify the concern (sounds better than complaint?)
If the concern can not be verified then the repair can not be verified either
Interview the owner (driver)

16. The Diagnostic Interview
Also called the Sherlock Holmes Interview
Interview the customer

17. Tech Tip
Make sure you are talking to the person that noticed the problem/concern or the person that drives the vehicle the most !
NOT the person that happens to be the most convenient to drop the vehicle off
Remember YOUR time is valuable also. 17

18. Is there a Problem? Describe the problem/concern
Is there actual a problem?
Does the customer know how to work all of the accessories etc.?
Does the technician know? 18

19. Sherlock Asks Concern just Start? Last Week? Last Month?
What happened or what repairs were done right before the problem started? 19

21. Interview the Vehicle

22. “The Milkman” My techs called me the “Milkman”
They always saw me with my metal tray with a handle carrying handheld diagnostic tools

23. “The Milkman”
What the “Milkman” was doing was going from vehicle to vehicle with the diagnostic interview sheet and performing basic “G” (General) tests

24. “The Milkman”
Results of my “visual inspection” and “G” tests would indicate what circuits or components I felt needed “P” (pinpoint) testing

25. TEST DRIVE THE VEHICLE

27. Milk the DTCs
A VERY good thing to look for when a DTC stores is the FREEZE FRAME
look at what the fuel trim is, especially when there is a P0420 catalyst efficiency code
Was the PCM trying to make a correction for fuel delivery?

28. Milk the DTCs P0420 Worksheet
1. Check for TSBs and calibration updates Check exhaust condition (leaks) Verify fuel control Replace the catalytic converter Verify the repair

29. ST & LT Fuel Trim

30. Fuel Trim Control
The fuel trim value is a very important diagnostic tool, if the fuel trim is very positive, like +23%, why did the PCM have to add some much extra fuel to it’s base calculation ?

31. “The Bends and Ends”

33. Checking TSBs FORD: 2005-2006 Crown Victoria LINCOLN:
Town Car
This article supersedes TSB to update the Service Procedure.
ISSUE:
Some Crown Victoria police and taxi vehicles built before December 13, 2005, and Lincoln Town Car Limo vehicles may exhibit a malfunction indicator lamp (MIL) on with diagnostic trouble code (DTC) P0305, possibly accompanied with P0316, P0171, and/or P0174, especially after extended idle. This condition may be caused by fuel vaporization near injector Number 5.

37. Fuel Cut-Off Mode

38. Comparing PIDs
A bad redundant ground circuit causing the TP and MAF to go haywire

39. Comparing PIDs
Take notice of unstable idle due to ignition timing changing

40. High Authority Inputs
The engine RPM signal comes from the CPK sensor and it must be able to calculate the engine speed very quickly
As the number goes up, the engine is going faster
This is usually the most important input

41. High Authority Inputs
This signal is used as the basis for the fuel injector pulse signal.

42. MAP Relationship

43. Take Note that frame #9 there is only 1.7 “hg of manifold vacuum
In frame # 17 there is 10.2 “hg of manifold vacuum

45. Narrow the problem to a system or cylinder
This is where the “G” and “P” testing comes in
Use a “G” (general) test to isolate the problem to a system or cylinder (or bank)
Then use a “P” (pinpoint) test to drive down that FUNNEL in order to find the problem.

46. Ford Motor Co

48. Finding the ROOT CAUSE
As stated in Jim Halderman’s Advance Engine Performance book
Always ask the “5 WHYS”
When you find the customer’s complaint, ask WHY 5 times

49. Finding the ROOT CAUSE
Example of this would be a P0420 code (low catalyst efficiency)
1 why – because the pre & post oxygen sensors reading incorrectly
2 why – because air fuel ratio is too lean
3 why – because the fuel delivery is inadequate
4 why – because the fuel pump pick-up is partial clogged
5 why – dirt in fuel tank

51. Verify the Repair & Clear DTCs
This is an important step for 2 reasons:
1 – YOU want to be the one to find that the repair didn’t work, not the customer.
2 – The are a lot of times that another DTC will not be set because there is a program that won’t allow a circuit to be monitored due to the current DTC.
This is known as a “SUSPEND” condition

52. Case Study Chrysler mini van no-start
Customer stated that it would not start unless he pounded on the dash. Finally, the vehicle wouldn’t start at all.
Step #1-Verify
Engine did not start
No spark
No Squirt

53. Step#2- Visual Inspection
Yep the customer pounded on the dash
So hard that the needles fell off

54. Step #3 Check DTCs

55. Step #4 Checked for TSBs-nothing that was related
Checked archives of
Bingo- found several fixes for wiring being burned near the CPK sensor

56. Step #5 Scan Data
No engine RPM while cranking

57. Step #6- Narrow Down

58. Step # 6-Continued

59. Step #7 Root Cause

60. Step #8-Verify Repair

61. Final Thoughts
How does the PCM put all this information together and run the engine?
You have to think like a PCM

62. Summary
We are recommending that you teach a diagnostic procedure in all courses
Repeat, repeat and repeat the process over and over
This way students will know what and why they are doing what test

63. Contact Information
Jim Morton
Jim Halderman