Anti-Theft/Vehicle-Security-System malfunctions and OBD code scanners

[BonzaiDuck]

Until September, 2018, my Trooper was just "my old ride", and I let my veteran mechanic call the shots about repair and maintenance, while I ignored typical owner fetishes, like cleaning the 5-year-old guano plops off the hood. Maybe once in a while I'd look at the EC in the radiator, check the oil or transmission Dexron.

Then, we were recycling old electronic garbage to the county hazardous waste facility. I coordinated with a friend across town, who had about six old tube-type TV sets, one of which was a big 32-incher and weighed a ton. We put it in the back of the Trooper, and I gave no thought to tying it down or padding the space between the TEE-VEE and my windows. We went over the gutter at the end of my friend's driveway, when we heard a "Crunch" sound. The TV had pitched backward to shatter my rear window.

The following morning, I noticed that the LED indicator at the Anti-Theft On-Off switch was flashing wildly. When it was behaving normally, it would flash on when you opened the car door, and then go back to sleep. My mechanic told me not to bother: people might see the flashing light and assume the VSS was armed. But I looked into the matter by checking the diagnostic charts in my Factory Workshop Manual. The symptom links to either a damaged connection in the wiring harness, or a "tripped" door/window sensor.

I just acquired an OBD I/II code scanner:

Actron CP9670 OBD Code Scanner

I'm just beginning to "study up" on this device, and its published guide, bundled in the package, doesn't get rave reviews from DIY users. It doesn't look all that great to me either, but the manufacturer has an online PDF that is much more thorough.

Like other OBD scanners, this unit has an ability to reset codes stored in the ECU or ECM. Or so the literature seems to indicate -- and you might then begin to wonder exactly what they mean by the word "reset".

But it dawned on me that -- possibly -- I don't need a mechanic to take apart my Trooper's back door and fiddle with anything there. It may be possible, I thought, to reset the VSS with the code scanner.

Am I dreaming? Imagining? Speculating? Or is this true? Could I . . . fix my VSS' behavior . . . with my Actron Code Scanner?

 

[mindless1]

You seem to be leaving out much detail.

When was the window broken? Was it repaired? Have you been driving it in a repaired state and the anti-theft light blinks different, but it has no impact on (for example starting) use of the vehicle?

Anti-theft is a manufacturer specific circuit not covered by OBD. While a scan tool can have manufacturer specific functions, you cannot assume an OBD code reader will unless explicitly stated, so no, it is not at all likely that the scan tool can reset the VSS.

Have you tried disconnecting the battery, waiting a few minutes then reconnecting it? Have you tried using a keyfob to disarm it?

I suspect that your security system should have been disarmed by using the key in the door then in the ignition (within 30 seconds or some other period). If it is still sensing a fault then the repair may not have been done properly and if that is the case, resetting the system may just cause it to sense the fault again.

What does the Isuzu Owner's Manual state? Resetting the security should be an owner function that should not need a manufacturer specific scan tool.

 

[BonzaiDuck]

I'll go back and review again the factory shop manual, but first time around, I saw nothing about this sort of situation.

Your questions remind me of concerns I had when first doing web-searches about this. I would run across forum exchanges with people who were locked out of their cars, unable to stop their cars -- all sorts of similar horror stories.

I never much used the Anti-Theft system. The few times I used it, I would feel mildly pleased that the wireless key-fob device would cause the car to chirp and unlock the doors for me. But the occasional accident caused me to avoid using the system anymore. For instance, the key-fob device would be in my pocket, and the wrong button would get pressed by accident. Then, I"d have to run out to the garage and make it quiet.

So I left the center-console panel switch for the VSS turned off.

When the TEE-VEE accident occurred, I had the window replaced and made sure the defogger was working again. No problem with any of that.

The battery has been disconnected several times, for periods of an hour or more, but this doesn't change the frantic flashing of that LED. Apparently, the LED itself can be disabled easily.

With this Trooper, the rear-window replacement propelled me to catch up on my annual visit to the mechanic for oil and a general checkup. I rebuilt the suspension (well -- new shocks and ball-joints with some incidental "need-to" repair-replacements). I fixed all the dents, painting the repairs properly to total invisibility. I started monitoring oil drops in the drop pan. I restored the paint finish, and added -- belatedly -- a grill-guard I'd wished for since I bought the vehicle.

Essentially, I told myself that I was going to restore the car totally -- as much as needed -- for my 2019 vehicle-budget year.

The VSS/Anti-Theft-system is the only thing left to fix, unless I want to worry about the burned out LED light for the transmission "Power" mode button. "Power" and "Winter" still work. I've noticed that the "Fuel Warning" light goes on more often than you'd suspect from reading the owners manual, which suggests that it may go on after a sharp turn or other situations, advising that this is normal. The vehicle is equipped with both the traditional fuel-gauge and this idiot light. They are controlled by a "Fuel Gage [sic Gauge?] Unit" which bolts onto a port in the gas tank. Two different circuits run from this device -- one for the traditional dashboard fuel-gauge, the other for the idiot light. I suppose the light is off for much more operational time than it appears to be on.

Otherwise, the Trooper is a very well-behaved vehicle. Personally, I've come to nearly believe the native American folklore and mythology of the Manitou, and I theorize that there is a "machine Manitou" for your automobile. This would explain why, when you polish the hood of your car, it runs better . . . .

 

[Paperdoc]

From what I know, the way the ODBII system works is that, whenever an error code occurs in the car's computer system it is stored in the computer and the warning light is activated. If it's a new error or a critical one the light will flash at you. But unless it's new or critical, eventually the light stops flashing and just says on.

When you use the OSBII code reader it reads the various stored error codes from your car. Then it uses some look-up table to tell you what that code means in words. Most car makers use the same codes for the same errors, so translating into words is easy. But some codes are maker-specific, and the ODBII reader needs access to an additional reference table specifically for your car to tell you what that means; otherwise it can only tell you the code number and let you figure that out. Merely reading the codes does NOT remove them from the computer's memory of error codes.

You are supposed to use that info to investigate and fix the problem at its source. Once you have fixed them all (or, decided it was a temporary condition you can ignore), you can choose to Delete all the error codes stored - that's the RESET option. This wipes them all out. So when you finish and disconnect, the light on the dashboard is off, and the system starts fresh. BUT if you did not actually fix the original cause of any code, the same error may happen again and the light will start flashing to tell you there is a new code stored that needs attention.

Disconnecting your battery for a while and then re-connecting is anohter way to do a RESET. The computer needs power to keep stuff in its memory, so the disconnect wipes the memory. But the same thing applies - if the problem is still there, the error will be recognized again. You say that, even when this was done AND the window had been replaced, the flashing light continued. To me that suggests two possibilities. One is that the repair job failed to re-connect the window damage detector system so the it still is sending back to the computer a "broken window" code. The other is a vague possibility that the anti-theft system is not part of the general car computer system, but a separate sub-system that was not reset by the battery disconnection process. Since you have a new ODBII tool, use that to read your codes. Most should be identified by clear words, but the one for a broken window may not be since it is maker-specific - you may only get the numeric code. IF you are satisfied that all of the error codes have had their causes fixed, RESET the system, disconnect, and see whether the flashing light returns. If it does, re-connect and see what new codes are there. If it is the same anti-theft warning of some type, you know either that you cannot reset that warning, OR that the sensor that trips it has NOT been restored by the window replacement. In that case, if you cannot get the sensor fixed, you can just ignore the light. BUT that also means that you will NOT be alerted to any NEW codes from some other flaw, so you will need to get into the habit of re-reading all your ODBII codes to be sure you have not missed some new important warning.

 

[BonzaiDuck]

Thanks, Paperdoc. That gives me more information with which to proceed.

The "Anti-Theft" system has a "Vehicle Security System" module component about the size of a bare SSD. I had found them new as OEM for sale -- about $300. But I don't want to buy one unless it's required to solve the problem created by the broken window. I never much used the system over several years. If I can fix it, that will be great. If I can't, it doesn't seem to affect much else.