electrical diagnostic practices/procedures

**jick.cejoco** · October 20th, 2023 07:15 PM

in most of general motors, i.e. Cadillac,Chevrolet,Buick, Oldsmobile, Pontiac and GMC, discourages technicians from poking into the wire insulation to make measurements or continuity because it breaks the wire insulation and therfore becomes a conduit for moisture that causes "ghost" problems. motorage discourages technicians from backprobing terminals because it can "mask" a potential cause of electrical anomalies or problems. it could "accidentally fix" a problem and could be a potential backjob. the question now is, which method do you prefer in wiring diagnostics?

personally, if i have access to the wring, i pierce the insulation to make measurements or diagnoses. the question now is: how about the wire insulation injury?
with this, i use liquid electrical tape after the testing to seal off the wire insulation injury. in the absence of liquid electrical tape, i use acrylic nail polish to seal off and prevent water intrusion into the wires. afterall, the most sensitive wires are the ones that lead to control modules. which, in most cases, a very confused and uncertain technician let alone a "mechanic" always blames the computer.

**jick.cejoco** · November 8th, 2023 09:23 AM

With today's cars that have a myriad of microcomputers on board, it is risky to disconnect the battery to check the function of the charging system. the high voltage spike/surge can cause trouble to the sensitive electronics. never disconnect the battery terminals with the ignition switch in the ON position.

**baludoy** · November 8th, 2023 10:08 AM

Originally Posted by jick.cejoco

With today's cars that have a myriad of microcomputers on board, it is risky to disconnect the battery to check the function of the charging system. the high voltage spike/surge can cause trouble to the sensitive electronics. never disconnect the battery terminals with the ignition switch in the ON position.

How about when charging the car's battery using ctek and the like? How safe is it really?

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**12vdc** · November 8th, 2023 10:52 AM

I always charge the battery with engine off, doors locked & hood switch jammed. It may take longer to charge if unlocked, anyway the BCM will shut-off after several minutes of idle state. Charger could pump up to 17Volts esp when desulfating mode.

**oj88** · November 8th, 2023 11:11 AM

The battery should be disconnected from the vehicle when running any desulfation/repair modes. Some chargers are smart enough to disable this mode if it senses the vehicle electronics. Others will have a warning label discouraging the use of this mode while the battery is still connected to the vehicle.

**12vdc** · November 8th, 2023 12:02 PM

Then you will have to use another tool to avoid losing car electronics memory, or it may cause check engine light if the sensors are sensitive enough to detect delays in low voltages triggering a false alarm.

No harm done to all the vehicles I've charged with the 7-stage charger that comes built in automatic desulfator.

**oj88** · November 8th, 2023 01:03 PM

Originally Posted by 12vdc

Then you will have to use another tool to avoid losing car electronics memory, or it may cause check engine light if the sensors are sensitive enough to detect delays in low voltages triggering a false alarm.

No harm done to all the vehicles I've charged with the 7-stage charger that comes built in automatic desulfator.

I don't think those chargers defaults to desulfation anyway, unless the charger logic deemed it necessary after assessing the battery's health. On some chargers, this mode must be triggered manually.

When I worked on one of the headlights in my car, I needed to remove the battery to gain better access. I used a discarded 12V UPS battery connected in parallel before disconnecting the starter battery. That way, the system never lost power. Putting it back is simply the reverse.... I only took out the UPS battery after the starter batter was back in-circuit. This is a good alternate use of a jump pack if you have one.

**yapoy86** · November 8th, 2023 04:14 PM

Originally Posted by oj88

The battery should be disconnected from the vehicle when running any desulfation/repair modes. Some chargers are smart enough to disable this mode if it senses the vehicle electronics. Others will have a warning label discouraging the use of this mode while the battery is still connected to the vehicle.

agree.. in my ctek charger, desulfation mode voltage is at 15V, which maybe too high to modern electronics running at 14.5volts

**Walter** · November 8th, 2023 04:34 PM

Have run CTek desulfation mode several times with battery connected ...

**jick.cejoco** · November 8th, 2023 05:20 PM

Originally Posted by yapoy86

agree.. in my ctek charger, desulfation mode voltage is at 15V, which maybe too high to modern electronics running at 14.5volts

some toyota cars of the 90s, the system voltage can go as high as 15.1 volts without damage to the systems. the keep alive memory (KAM) such as electronic tuned radio, pcm memory, body control module memory, immobilizer , can be kept by using a memory saver conndcted either to the DLC3 or to the BAT of the alternator with a 12 volt battery. doing this, the doors closed, all swiltches turned off.