Starter and theft deterrent
system diagnostics

The electric starter motor has taken the place of the hand crank a long
time ago. Although, the actual starter motor has improved quite a bit, its
function is still the same. Just like most of the systems in today’s cars,
the simplicity of the basic functions of a circuit remains the same, but
the way that it gets its current/voltage from point A to point B is quite
different from years past.

Today’s vehicle can have numerous additional features to the starting
systems.  Remote start, auto start, and auto cranking are just a few. 
And, with a lot of these systems an anti-theft system is directly involved
with the operation of the starter motor.  Originally, the ignition key was
wired from the ignition switch to a neutral safety switch and then directly
to the starter, which made diagnosing a problem a pretty straight forward
repair.  The biggest concerns were whether or not the battery was up to
the job, the condition of the starter motor and related switches, or if the wiring was intact. Sure, all that can still be an issue, however… there’s a lot more to it these days.

Typically you don’t want to see a voltage below 9.5 volts while load testing the starter motor, as well as checking the amperage draw is within the manufacturers specifications.  But, these readings are only of any value if the starter is able to spin.  Where do you go if you turn the key and nothing happens and you’ve already eliminated the usual suspects such as wiring and basic components?  Now it’s time to look at all those “extra” electrical systems that make up that particular vehicles starting system.

Starting the starter diagnostics

Visually checking battery connections is the first place to go, obviously, without a good battery (12.6v @ 70 °) you can’t properly diagnose the rest of the system.  Clicking, chattering, or a snap and then no voltage at all are good indications of probable connection failures.

A wiring diagram is the next best source of information.  With a lot of vehicles today a starter relay is involved rather than straight from the neutral safety switch.  However, the relay may be controlled by a PCM or a theft control system.  This is something you’ll have to research through the wiring diagrams. 

So, you’ve checked out the wiring diagram and you have determined that it is a PCM controlled signal and that this vehicle uses a factory theft system as well.  How do you eliminate each of the different processes needed to get the starter to spin?  That’s a good question, because, it’s not as easy as merely looking at the wiring diagrams.  You’ll also have to know the process the manufacturer uses for the starter/theft system operation.  This may not be all that clear on a wiring diagram, but should be on the description pages of the starter or theft systems. (On some cars just having the hood open can keep the starter from operating, while others rely on the theft system to disable the starter, or both.)  You’ll need to study all this information in order to properly diagnose the starting system.

Theft systems / starting system diagnostics

Getting into the theft side of a no crank condition is unique for every different make and type of car.  Not only for each different manufacturer, but also for their different models as well as the year of manufacturing.  GM for example, has used several variations of their PATS system over the years, and with each progressive changes the systems get more elaborate than before.  The first systems used 15 different resistor pellets embedded into the key.  This early system had one major drawback which was the two small (usually white) wires that would break off from the key tumbler.  These systems could be easily bypassed by alarm companies installing aftermarket alarms, and offered very little challenge to a novice thief. Here’s a list of those pellet values and how they worked.

.  By far, these are the easiest early systems to bypass. These codes are nothing more than different resistance levels (ohms). 

The factory override codes are listed as follows:

GM VATS Override Resistors 

OHMSResistor Color Code
392Orange, White, Red, Black
523Green, Red, Orange, Black
681Blue, Gray, Brown, Black
887Gray, Gray, Violet, Black
1130Brown, Brown, Orange, Brown
1470Brown, Yellow, Violet, Brown
1870Brown, Gray, Violet, Brown
2370Red, Orange, Violet, Brown
3010Orange, Black, Brown, Brown
3740Orange, Violet, Yellow, Brown
4750Yellow, Violet, Green, Brown
6040Blue, Black, Yellow, Brown
7500Violet, Green, Black, Brown
9530White, Green, Orange, Brown
11800Brown, Brown, Gray, Red

These are the exact values, but you’ll find if you’re within 10 or 20% of the value it will still work fine.

Transponder security systems

The transponder key has taken over as the norm these days. The transponder is nothing more than a radio signal that projects its signature code to a pickup coil unit mounted around the key tumbler. But, with the variety of systems out there you’ll need to figure out what generation of theft system is used in the vehicle you’re working on.

Which one am I working on?

My preferred method is to go OEM1STOP.com and find the manufacturer of that vehicle or go to NASTF.ORG.  This is where you’ll find the security info and what tools you’ll need to program keys and of course, lots of other good information directly from the manufacturers.  A lot of sites may require some form of payment for the use of their information, although, Hyundai and Kia are free. (As of now)

Once you find the information on what type of theft system is on the particular car in your service bay you’ll be able to proceed with the proper steps in diagnosing the no crank condition.  For instance, on the Ford page you’ll find the “programming and initialization” page. Even though some of the sections require a fee there is still a lot of information there for free if you click on that heading.  Such as the section which will list the various vehicles and the type of theft system it was manufactured with. This way you’ll know before getting to deep into the diagnostic procedures whether or not that particular car has a starter interrupt, auto start, or is PCM controlled.

Programming Keys

Obviously, a key that isn’t programmed to the car isn’t going to start it.  And, if that’s the issue you’re having there are ways to solve this problem without having to send the car on another tow truck ride.  You could invest into the various factory scanners to do the job, or you could see if there is a way to program a key without the use of a scanner. 

Go to aloa.org (Associated Locksmiths of America) this is not a free site, however after you pay for the service, and pass the background check you’ll be able to receive the needed information to program keys without having to have the actual factory tool.  For a lot of independent shops that do a lot of various models and are doing a lot of key programming this could be invaluable.  As well as the various methods for reprogramming keys you’ll also be able to find out about any special tools required and where to source those tools.

Starter immobilization quick test

Let’s say you just can’t get on the websites to find out whether or not the car in your service bay has a starter interrupt feature or not, but it does use a transponder key.  Try this little trick.  Assuming it does start before you try this of course, remove the key and cover the transponder part of the key (entirely) with aluminum foil. The foil will block the radio frequency from the key to be passed onto the pickup that surrounds the lock cylinder.  If the car is equipped with the starter immobilization and you try to start it with this “aluminum key” the starter shouldn’t spin, and the security light will continuously be flashing.  It’s not full proof but, it will help you eliminate the guess work of whether or not the car is equipped with a a starter immobilization or not.

I’ve only brushed over some of the various sites that you can find the needed information. Hopefully, with the aid of a wiring diagram, the manufacturers website information, as well as the service codes your well on your way to solving that no crank condition. It truly is a global market these days, and so is the diagnostics.  No longer can one book or one method solve the majority of diagnostic issues. You have to be diversified into knowing how to navigate a manufacturer’s website as well as the various other tools of the trade.  Having the right websites, diagnostic tools, and information at your disposal is what will make the difference in solving the problems with today’s cars.

Knowledge Page link