Here are a few random scope captures from some of the cars we worked on the last few weeks.

In this one, the Grand Am would intermittently crank but not start. This was after taking care of a bad crank sensor, and fixing a wire that had been cut to the ignition switch Passlock sensor.

This was one of the events where the car cranked and started, but it did not start right away.
The tan trace is power to the coil pack, the green is the electronic spark timing command from the PCM to the module,
The red is the reference signal from the module to the PCM, and the blue is the crankshaft position sensor signal.

Here you see a close up of the failure, during key on you can see the tan at 12v, but it falls to 0v when the engine is being cranked. The blue trace shows the crank sensor signal, but with no 12v to the module assembly, you don't see the reference signal to the PCM to inform it that the engine is indeed being cranked.

Here is a Chevrolet Prizm electrical system test. The customer had a battery installed but wanted to be assured if everything else was OK or not. This first capture is the starter draw and batter voltage during cranking.
 The blue trace is the current and this is a classic drawing of a good starter, battery, and cable connections. The initial draw is over 600 amps for a brief moment and the battery is only pulled down to 9.2v. This occurs just before the starter starts to spin. Once the engine is cranking a normal cranking amperage is seen in the 150 amp range.

Here in the next capture we tested the alternator at 2000 rpm and it is putting out 70 amps and the alternator ripple  waveform shows that all of the diodes are good. A bad diode would have a repeating pattern  of distortion instead of all of the peaks being uniform.

The last thing to check is for a drain on the battery. This test  passed with no parasitic drain .

By the way, remember this from a few weeks ago? This is just a bad starter from a Honda and it makes for a good comparison for the capture on the Prizm.

#GrandAm, #alternator, #drain, #Chevrolet, #Passlock

Commentary and response to an article found in the Philly Inquirer

Here is a link to an article in the Philly Inquirer and the e-mail that I sent the author.


http://articles.philly.com/2014-02-12/business/47238848_1_pep-boys-philadelphia-auto-show-technicians




Hello.

After some 38 years in the trade as a technician, (I also own my own shop and teach continuing educational classes nationwide) I have a problem with the article that appeared in the Philly Inquirer.

I'll refer to my blog where you can see a post written by one of the best technicians in the country, and you can also find this same post in a fixed operations managers forum on linked in. (I sent you a request but have not see it be accepted).

Here is my blog. http://johng673.blogspot.com/

The simple facts amount to your article was really nothing but an advertisement for UTI to try and attract students to try and get jobs that they cannot possibly be trained for in that short of a period of time, and even the most stellar students if they have all of the natural gifts to be a great technician are decades away from being that person when they do graduate. These kids are being saddled with a huge debt to try and get entry level jobs in a trade that routinely eats its young.

BTW the fixed operations forum on Linked in is here..

http://www.linkedin.com/groupItem?view=&gid=3945201&item=5839734171479601155&type=member&commentID=5839741901611241472&trk=hb_ntf_LIKED_GROUP_DISCUSSION_COMMENT_YOU_CREATED#commentID_5839741901611241472

It should be noted that the thread is getting next to no response at this point essentially because the real atmosphere in the workplace as an automotive technician is on display. In any other career advice like work harder than the rest, be the first one in the door and the last one to leave should lead to success. But as my blog demonstrates the only thing that is important to these managers is how many hours a tech produces, even if the way the hours are calculated is terribly flawed, and even dishonest. Before we try and attract the young people that the consumer needs us to have, we need to genuinely fix the compensation packages and working conditions of the current technicians. Your article made it seem like there is a lot of money to be made. How about going to the Bureau of Labor Statistics and try to confirm that position.

Here is a link.

http://www.bls.gov/ooh/installation-maintenance-and-repair/automotive-service-technicians-and-mechanics.htm

With the quality of todays automobiles climbing, there are fewer repairs to do than there was just a few years ago. While the technician workforce, especially the real top techs are aging and leaving the trade, there are in fact too many shops and techs. That's a two-fold problem because anyone coming in won't generate enough income to make it worth sticking out and life is going to do what it is going to do and the senior techs will all be gone, with no-one to step in and take their place. When you article said that dealerships will be happy to see Ms. Lukatchik in two years, the reality is she won't be who you need the dealer to have for at least fifteen to twenty years. Even then not she nor anyone else can ever be the master technician that we had in the shops when I was a kid just starting out. Back then there wasn't much that really needed to be learned, today there is so much that the best anyone can do is specialize in one or two areas.

Please follow up on this.
John Gillespie
ASE CMAT L1 A9
Owner/ Technician/ Technical Writer/ Instructor
Electronics/ Diagnostics Specialist.
724-728-5484 Shop
724-312-4939 Cell

#Philly Inquirer, #Auto Technician, #Auto Mechanic, #Automotive, #Service, #Technician

This post was written by James Avery and posted in the iATN

If you want a little insight into what diagnostics look like on the newest cars this is a great example. I'll comment on this at the end.

A 2014 Corvette with 1500 miles came in with a complaint of
intermittently the radio and/or Nav system would shut off at
times for 2 or 3 minutes and then come back on by itself and
operate normally. Scanning the infotainment system, U0028
was set as history in the radio. This signifies a MOST ring
break in the past.

Looking at MOST operation, the MOST network is a two wire
twisted pair infotainment data bus that runs 100 times
faster than high speed GMLAN. It is a unidirectional ring
network that has a master module that serves as a MOST to
LSGMLAN gateway. There are other satellite modules in the
MOST ring. Requests are usually supplied by other non MOST
modules connected by a LIN network, The request is sent by
LIN to the MOST module which sends it along the ring network
and watches for a return. Each MOST module watches the
module before it in the network for data. This occurs in an
downstream position only as the ring is unidirectional. The
modules are assigned places in the MOST ring by the master
module and assigned a numerical position ID number.

Still with me? If a module loses data from the module
upstream of it in the ring, this is known as a ring break.
At this point, the module first losing data will declare
itself on the ring as the Surrogate MOST Master Module. This
happens ONLY while the ring break is active. Surrogacy is
cancelled if the communication is restored. When the ring is
broken, only modules downstream of the break will send
information to the radio which usually is the MOST master
module. Ring architecture can be viewed on GDS2 as the Last
Working MOST ID of Node XX. XX will be the assigned ID
number of the module. The numbers will increase from node 1,
(usually the radio) through the other nodes in a downstream
direction.

On this vehicle the node IDs are as follows....

Node 1 - radio

Node 2 - Audio Amplifier

Node 3 - Human Machine Interface Control Module

Node 4 - Instrument Cluster

The Surrogate MOST Master Upstream Position value on the GDS
display was NONE as the ring break was not evident at the
time that I looked at the vehicle. How do we diagnose it? I
had two options. One would be to check the entire MOST
network ring for module/connection problems. The other would
be to test at the time of failure when the ring break
reoccurs which would supply me with information about the
declared Surrogate MOST Master module. I drove the vehicle
with a laptop, monitoring data. After 12 miles, the radio
shut down. Looking at the radio data stream I saw Surrogate
MOST Master Node Upstream Position value was 2. I drove back
to the shop and the radio started working again after a mile
or so.

Now I know the module that declared itself as the Surrogate.
The Surrogate MOST Master Node Upstream Position value again
reads NONE as the problem is not occurring again and
Surrogacy is no longer enabled. Although the MOST ring
information is transmitted downstream, we need to look
upstream for a diagnosis. The upstream position set was
position 2 so we need to count backwards on the ring from
the master module to find the position, not the assigned ID.
The last MOST module on the ring is the Instrument Cluster
ID 4. This will be in position 1 counting upstream. The next
module is the HMI module, ID 3. This will be upstream
position 2. Therefore the HMI module was the module that
established Surrogacy during the ring break. Still with me?
The HMI module is not a failure point and is operating
correctly. It just lost communication with the module
upstream of it in the MOST ring that was transmitting
downstream to the HMI module. So, the ring break must have
occurred BETWEEN the next upstream module which is the Audio
Amplifier, ID 2 and the HMI module, ID 3 in the MOST ring.

Checking the wiring pin fits at the HMI module inputs, I was
able to re-introduce the ring break by wiggling the wires
and found a loose pin fit at one of the connectors. A new
terminal fixed the problem.

------------------------------------------------------

• I wonder how aware most managers are of the fact that in order for top techs to deal with today's cars we cannot rely on just the training that is typically provided. Many of us write up repair events such as what you just read through sometimes as a straight essay, and quite often just short of revealing what the failure was and letting the other techs practice looking up the information and figuring out the problem the best that they can without actually touching the car. We will do things like ask for a measurement at a particular pin connection with a scope/voltmeter and of course even send snapshots of serial data back and forth.
  
  Maybe you knew, maybe you didn't but most of us have been very active at doing this for the last fifteen to eighteen years. BTW James has another one out that he wrote after this one and both of them demonstrate that the cars can only test themselves so much, and the tools we have otherwise cannot diagnose the cars. It takes techs, dedicated, skilled, and committed way beyond what the compensation for the effort returns. The ugly truth about flat rate is for now that Corvette paid James straight time. If I was I the stall next to him while he was fixing this and doing customer pay front end and suspension work, I would have generated three to four times the income that he got paid.
  
  Now how does that make any sense?
  
  We always hear the advice of work smarter not harder. That simple line essentially suggests there is no reason to attempt to learn how to solve that Corvette's problem and is the heart of why it is difficult to find qualified technicians today. The need for speed and the one sided evaluations of the techs from the flat rate perspective has worked to discourage us from making the kind of investment in ourselves that we could grow into being the kind of technician that James is. What's even worse is many of the comments and especially the political pressures in the bays serves to duly punish anyone who genuinely tries. I hope you really hate seeing it written that way, in so much as to not just try and shout it down but to look closer at what really has been going on in all of the shops, and start managing to correct it. Straight time for that diagnosis and repair, what a joke. Soon the Corvette will go off of the straight time and that would probably be assigned the .3 like all of the other GM diagnostic routines that actually still pay anything. Of course the tech could beg for additional time which may or may not be granted.