Chevrolet Cruze Forums banner
1 - 3 of 3 Posts

·
Banned
Joined
·
10,296 Posts
Member was me, high point contact resistance in the ignition relay, but not the only problem, also with the new style negative battery cable crimping bare copper wire within the confines of the negative battery terminal. Turns brown, copper oxide that is a very good insulator. Copper oxide rectifiers have been around for over a hundred years, so nothing new.

Mine is now soldered, by me, positive battery cable terminal is crimped on the same way. All they had to do was to stick that bare wire in a solder pot to prevent this.

Also it was dumb to place all those positive battery cables on top of the battery. Even a maintenance free battery emits sulfuric acid fumes that augments this corrosion. Constantly keeping those clean and coating with dielectric grease that helps to retard corrosion. Yet another age old problem when electrics are placed any where near a battery.

With regards to point contacts, been a problem every since Moore invented the telegraph key, in particular when switching inductive loads. Back electromotive force generates an arc that carbons up the contacts. Any engineer worth his salt knows this.

Another item that hit the history books is plating the copper wire strands, still have several rolls of wire that are plated left over from the 60's, practically all bare copper today. So don't wonder why you have problems.
 

·
Banned
Joined
·
10,296 Posts
An inductive load is any thing with a coil of wire, relay, starter solenoids, motors, an ignition coil is a good example of this. With only a 10:1 turns ratio from secondary to primary, the instant the circuit is broken 12V at the primary can generate 40KV at the secondary, all deals with rate of change of the current flow. Ha, basic stuff, that collapse generates a spark across point contact relays contacts, and the arc causes contact damage, actually the best material to use is tungsten, it can take the heat. Another hazard is when the contacts close with an incandescent bulb, cold resistance is very low resulting in a surge current that greatly exceeds the contact current rating. Only good engineers know this stuff.

Silver is the worst plated on a copper contact, idiots just read the conductivity of these good metals, but they cannot take the heat. A$$holes for lack of a better word, specify this because of the higher conductivity, think they can get by with a smaller contact, while tungsten can take the heat, it does have a greater resistance, solution is simple, use a larger contact. But then you have more a$$holes called bean counters. But this is only one of the problems.

The key problem is voltage drops across what you would expect to be a short circuit with zero ohms of resistance. The most negative point in a vehicle is the negative battery post, not the terminal that wraps around it, but the post itself. And likewise the most positive point in the vehicle is the positive post of that same battery.

Using these points as a reference and with now a very inexpensive VOM can check for voltage drops, a key ground point for practically all the vehicle electronics is the engine block itself. But too measure voltage drops, need a large current flowing, easy on a vehicle, switch on the headlamps, blower motor, rear window defroster, plenty of loads.

In my Cruze, with the black lead connected to the negative post of the battery, red lead on the engine block, the block was over 2 volts more positive, by working backwards, found the major voltage drop to be between the exposed end of the negative battery cable at the radiator ground point and the terminal of the negative battery post clamp. Took this apart to see bare corroded copper wire inside of that negative battery clamp. Drilled a hole where that crimp is so I could pull out the cable from the clamp, cleaned it, and with a propane torch, securely soldered that connection. Putting about 70 amps of current through it, that voltage drop changes from over 2 volts down to about 16 millivolts.

Working on vehicle electrical is always awkward to say the least, no points to measure, for a wire need a stick pin to make contact, but put a dab of RTV on it, or moisture will get in an corrode it.

For that ignition relay, had to use male and female 3/16" terminals plugged into the PCB board with the relay hanging on to it, four pins. With ignition on, was measuring over a volt across closed contacts, not good, and this voltage would change whenever I would switch the ignition on and off, erratic contacts.

To ease matters, pull all the relays out on my workbench energized the relays with a 12V supply and ran a constant current of ten amps through each one and measured the voltage drop, the rest were good, but for how long.

Really feel DRL's are a stupid safety feature, when conditions were right, we use to have brains to switch on our headlamps. Using lots of point contact relays for this "feature", and with a dirty contact, can get no headlamps at all, not very smart from my experience.

Ha, back in the 60's was working with Bell labs on the development of touch ton, they had literally thousands of stepping switches and point contact relays with 24/7 crews constantly reburnishing switch contacts. Solid state could be switched zillions of times without failure, and saved the phone companies millions in labor charges. But what did they do? Charge a lot more for touch tone.

Use to working with crooks.
 

·
Banned
Joined
·
10,296 Posts
Without my say, was dumped on this planet in 1939, incredible the technology developed in this country between 1942-1945, use to work for these incredible WWII engineers, yes smokers and coffee drinkers.


Soon to turn 77 years of age, but had a forced retirement five years ago, namely because my company was forced to move to China.

Ha, showed up to work in the late 70's wearing blue jeans, when question, not here for a fashion show, here to work, was a hands on kind of a engineer, and you don't find problems on a piece of paper, find them in the field. Ha, these young kids running simulation programs, don't even have enough sense to replace a burnt out light bulb without running a simulation program first.

Using mixed signal application specific technology for an IC engine that is practically all analog anyway, a chip can be developed with self correcting logic that would be 100% reliable. But know, use an 89 cent microcontroller instead, its cheaper and store code in flashram. Really crazy, electrical glitches can leave you stranded.

Ha, you only have one drive belt to replace, if the AC compressor breaks it, you are also stranded. Maintenance is history, only thoughts are speeding up the production line.
 
1 - 3 of 3 Posts
Top