The end of an era in troubleshooting techniques

I started in the garage in 74 (with VW) and I certainly don’t remember this and with every VW getting a compression test (at tuneup time) you would think I would rember getting in 20 cars a day,slapping on the seatbelt and turning the key as my first job was turning the key for mechanics that were doing compression tests.

Here is a link and a paragraph about these starter systems…

http://www.mgb-stuff.org.uk/electricstext2.htm

North American 1974: A rather complex interlock system requiring a box of electronics with no less than 12 connections plus 10 other components was installed at the behest of the American authorities. One of these components was a 500mA fuse feeding the electronics. This lasted just one year as reputedly American manufacturers complained, successfully, that the requirements were too complex to implement. With this system there was a drivers seat switch as well as the passengers. Much as before under the appropriate conditions the audible and visual warnings would sound, but additionally the starter circuit was interrupted to prevent starting of the car. There was the same gearbox switch as before, but what part that played in the logic I don’t know, I’ve never seen a description. One wonders what different logic would need to be applied if the car was in a gear as opposed to not being in a gear. Whilst there is no need to disable the starting circuit there is no reason not to either. I don’t know why a box of electronics was needed, the starter inhibition could have been achieved with a simple relay with a normally closed contact, operated at the same time as the warning light. Possibly the audible warning was on a timer, as with the later system, and possibly the visual warning was on a longer timer as on more modern cars. Although it shared the buzzer with the seat-belt system the ‘key in, door open’ operated independently. Presumably the drivers seat switch was required so that one could lean in and start the engine for maintenance reasons without having to have someone - or a large weight - in the seat with the belt fastened! Must still be a pain when manoeuvring the car in and out of the garage, though.

Some VWs in the 80s were equipped with a starter interlock although I do not for the life of me remember which which ones or the years.

I remember this because I was dragged into several “incidents” in which a salesman promised someone that the starter interlock system could be added on a few minutes time. This was of course news to us in the service department and ticked off some car owners when they dropped by a week or so after the sale to get this done while they had a cup of coffee.

“Just a few minutes to change the seatbelts” was what these people were told. Ha.

I was interpeting “What Who’s” post as saying that every car sold in the U.S came equipped with this system by law at some time in the past. Is it now being said that this system was not required but the owner could have it added on if they wanted it?

I can’t visualize how the letter I would send to my representive in Congress would read in order to get him to look into this. I do think if I had the oppourtunity to use a Congressmans influence there are quite a few issues that would come before this one.

“An End of an Era in Trouble Shooting Techniques”, Spending money and time swapping modules is considered trouble shooting?. Its interesting, if a Vehicle dealer or swaps or hangs parts in the “hope” of fixing a vehicle, they are considered incompetent. Yet this is acceptable for small independants. I am not pro dealer nor am I pro independent, I am however pro accurate diagnostics… There are misfits on both sides. If you have a scan tool, a Digital Volt Ohm meter and a wiring scematic, figure the problem out… Being a real technician is not saying to a customer, we’re going to try this, then try that, Oh an by the way we swapped your equipment with another customers… Being a technician is, we performed indepth dianostics, and the results show X, WE traced the problem to Y and we know Y will fix it… One Shot, One Kill.

Lets look at VIN loaded modules found in current vehicles… There are reasons for this, and None of them are designed to “Piss off” technicians or customers or put the Independants out of business… The irritation factor comes as an aftershock… No one can deny that electonic complexity has exploded in the past decade (Electronic load based throttle control, stabilty control, Roll Over prevention, traction control, Theft immobilizer and multitudes of other electonic intensive features) Even the often overlooked simple things have a huge impact, like different gear ratios, different steering ratios, AWD vs Non-AWD will have major changes between vehicles in terms of software and Hardware.

All systems and their related modules communicate operating information via some form of data bus (CAN, SCP, CCD, etc…) In most cases there can be 3 to 4 modules (If not more) involved in controlling some output most people think is simple. (like Electronic Throttle control.) The public thinks very simply, Hit accel pedal, throttle opens, vehicle should accelerate, Right? They don’t know data from the ABS system, transmission data, VCT (Cam timing data), Engine and exhaust temps, MAF inputs are used. The data being transmitted between modules must be accurate… Especially for throttle control and Stability/braking control.

Lets look at an example, What if you were to swap in an ABS module into a like year vehicle (same engine, transmission, interior components, etc. Vehicle Looks identical) you may think all is well. What if the steering gear is different for the towing package that the donor vehicle had been equipped with… Most would say big friggin deal… Would the stability control syetm care?? The reality is that the stability control needs to know steering gear ratios… If you alter this calculation, the system would not function reliably or at all. There are legal ramifications to this… You alter (Unknowingly) the Stability control system, system fails to operate and people are killed or injured who is responsible? The list of things that could co wrong by swapping modules is endless… Now imagine someone swaps in a module from what they believe is a like vehicle module (Lets say customer did it), Now all hell is breaking loose. Nothing seams to be working reliably and the customer has just thrown in the towel and brings it in to your shop… What do you do??? Where do you start?? (Customers are always honest and forthcoming in telling you what they have been fooling around with)

The VIN Loaded modules are a step taken by the engineering departments to ensure that the module installed in a vehicle is truly the correct unit and software version for that vehicle… If someone tries to cheat the system, one or more of the modules are designed to recognize the incompatibility. Ultimately throwing up the red flag for other technicians to follow. Does it make things harder for everyone? Maybe. What it really means is that someone needs to actually do some work, and be a technician. If you don’t know what your are doing… Don’t touch it… If you really, really what to touch it… read up on the system, look at the wiring scematics, follow the pinpoint tests. If you just want to play, get ready to pay someone for their time to fix your mess… This may be a little cold, but I’m sick of customers making a huge mess then expecting me to fix it for nothing.

The days of Ignition Points, Carbs, vac advance are long gone… Electronics, Multiplexing and being able to perform proper electrical diag is here to stay. Either you learn how to do it right… or you stick to changing oil.

Excellent post.

I for one would not swap in a known good part for testing purposes,the biggest reason is that the part would not be returnable after you did so.

Every electronic component like PCM’s and module’s come with the disclaimer that if the part is installed it can’t be returned. Even if the packaging had been opened but the part was not installed it still could not be returned.

Then the issue arises of what happens when you install the new part(such as a PCM) and the new part gets zapped. Now you are stuck with a junk PCM…who is going to pay for it? The customer?

The technique of swapping in known good parts for test purposes is one that is presented to technicans in many FSM’s. I did not invent the practice. Perhaps those that object to the technique are not familar with how problems really get solved in the shop and are a bit of “book smart but can’t really fix anything”. At times the most expediant and praticaly the last technique you have left is swapping in a known good part. The technique is widespread,and was carried out with the blessing of the manufacture and not simply limited to this oil changer.

Oldschool is dead on correct about this issue and while it’s unfortunate it’s also a sad fact of life. I fail to see how anyone can be a mechanic and not have to resort to this tactic; which I agree is a kind of a Catch 22.

The factory service manuals even state this is to be done so what is the lowly line mechanic supposed to do when the FSM info runs out? Sometimes those diagnostics are beyond the capability of the dealer, the regional office, and even the factory depending on the problem. (Regarding the factory comment, most of those electrical components are farmed out and it will require specialized (and godawful pricy) equipment to test those particular parts. Equipment which the factory does not even have.)

Relying on a VOM as being the final word can also leave you up the creek. It’s quite possible to have a problem with a particular circuit and have the VOM show things are fine.
If one puts 100% of their faith into a VOM reading then they could very well up chasing their own tail at times.

So, what I’m understanding is that components are VIN-specific, and that non-compatible VINs will set a code?

For the owner/occasional repairman, it seems the upshot of this is that you can’t use junkyard parts to repair your ride as it ages?

Count me out…

That is a fair apprasial but as I noted GM started with the 2010 Camaro and added the rest of the “fleet” in 2011. The immediate effect that I see is with the Dealer mechanic. It used to be that your Service Manager or Shop Foreman told you to use the “stub in” process and the parts dept did not object so the mechanic followed orders and stubbed a part in. This technique can make for a very fast repair or a fast diagnosis confirmation (helps when a part must be ordered).

I used to keep a array of turn signal switches, headlight switches, power door switches and other various electrical modules for this purpose. How did I get these parts? they were warranty parts (parts that should have been tagged and destroyed after a period of time) but instead of being destroyed we used them for test purposes. This pratical solution worked well but at times you did need to request a new part from parts dept for this purpose.

I am not at all informed as to how far this “VIN tagging” so to speak will go. What I mean is perhaps the less complex parts will not be affected by the new Global Electrical Architeture concept.

I do respectfully disagree with the premise that anyone who stubs in a part is incompetent, should be relegated to oil changes, etc. That premise could be used in a classroom or by some engineers sitting around a conference table but in the real world not everything is clear cut, and that even applies to older and far more simpler vehicles.

While there are countless examples consider the following two from 25-30 years ago.
The Ford TFI module. Unless there is a hard catastrophic failure of that module (not often the case) then a mechanic can test those modules until the cows come home and there will never be a problem shown.

Same goes for the even earlier DuraSpark ignition systems. I’ve seen early 80s Fords in which every single test by the factory manual says there is no problem and the Snap-On module tester will back that up. Unfortunately the vehicle will not provide a spark at all and a random guess at the module or the Hall generator would fix it.

Incompetence? I don’t think so but if the posters who think the above is a sign of incompetence then I would like to hear what they would have done in this situation.

The silence here is deafining.

ok 4450 is right about vw’s. Had a salesman that could not figure out how to start the vw.

Seat belt had to be latched.This was in the early nineties, used vw.

oldwrench, is that the only thing he has said in this thread that he is “right on”?

I just read in USA Today that Ford is coming out with a “Red Key” for one model of its Mustang. The car will come with two keys, one that “sets” the ECU program for daily driving and a second “red key” that “sets” the ECU parameters for performance. According to the article, the engine even sounds different (I’m guessing it’s because the valvetrain parameters are changed via some type of intelligent valvetrain technology).

The keys will now determine the ECU program parameters used. Imagine how much fun THAT will be. And imagine how much a spare key will cost!

My thinking is we will see a lot more sensors, controllers etc. that will not work the traditional way of analog/binary inputs/outputs simply because every device needs to have there signal wires go back to the ECM. My thought is the ECM will act more like a server, and all the sensors, controllers will be network devices all communicating back to the server on a single communication buss. At this point there will be no way of trouble shooting without the proprietary software. And replacing a network device will require the software to discover, and address the replacement part back into the network.

I was thinking of how easy it could be to store parameters on how the car was driven on this key.

I was talking to a bud the other day on a similar subject, He owns a shop but is not enjoying car repair as much as when he got into it. His take was cars used to be a repairable item, now they are a disposable item. It got me thinking of starter motors, you used to be able to rebuild them, now you can’t, the same with gas pumps, pretty much the same with anything you used to be able to fix is now toss the old and buy a new.

oldschool, totally off-topic, but do you own a gray Chevy Impala from the late 60s or early 70s with the license tag “OLD SCL”? If so, howdy, neighbor.

 1974.  It was such a stupid idea (since it added multiple failure points that would *keep the car from starting*) that it was eliminated by 1975.

 Also..before you all freak out (too much at least) it seems that per this:

http://www.sandyblogs.com/techlink/feb2010techlink.pdf
This affects the BCM (Body Control Module), ECM (Engine Control Module), IPC (Instrument Panel Control module), HVAC (Heating/Ventilation/A/C), EBCM (Electronic Brake Control Module), SDM (Sensing & Diagnostic Module) and the SCLCM (Steering Column Lock Control Module). Oh also the radio, but factory radios have been weird about this for a long time.
Oh and the culprits… 2010 Chevy Camaro, Chevy Equinox/GMC Terrain (the same vehicle…), and Cadillac SRX. They also claim in a seperate press release that the 2011 Volt “premiers” the Global Vehicle Electrical Architecture (even though it doesn’t.)

 First off, I do think this is stupid, don't get me wrong.  BUT -- 

 1) These computers are all involved in the anti-theft system, so that's the rationale they have for sticking VINs in all that.  It sounds like on cars without this system, swapping a few of these computers can result in a functional, but with the wrong VIN (scan tool shows the VIN of the "donor" car) and worse wrong mileage (the odometer's electronic, so it'll show the mileage of the "donor" car too!)  Well, let alone other possible problems.

 2) It doesn't involve ANY other components (not window motors/switches like the Ford example above, no relays, no sensors, etc.)  So really, it ONLY affects swapping an entire computer out, not any ordinary vehicle components.  Which leads me to ...

 3) It's highly unlikely any mechanic, shadetree or not, could reliably come up with a compatible computer anyway.  My friend had a 1988 Olds, where the ECM circuit board cracked.. picked up at a replacement at the junkyard, IT had cracked!  (It was a repeat failure on that year and make apparently.)  Thats the only instance I know of of an ACTUAL computer failure, as opposed to someone misdiagnosing a wiring fault as a computer fault and replacing it didn't help anyway 8-).  Back then, they used that computer for 2 or 3 model years.  More recently, it's really not reliable to swap a whole computer over even within the same model year anyway, they change stuff too often!  The most noticeable problem with a computer swap even in the 80s models was putting an automatic transmission computer into a stick; it'd cut the fuel entirely when your foot's off the pedal, which would save some gas on an auto, but on a stick meant immediate stalling as soon as you put in the clutch pedal.  Another common problem is swapping a computer from a vehicle with different diameter tires, resulting in both an inaccurate speedo and (since the effective gearing is wrong) engine tuning that might make sense on the "donor" but not the car the computer goes into.

 In summary though, this is making a mountain out of a molehill, swapping normal components still works, just swapping the computers doesn't, but that is generally a bad idea anyway.