Solving a Chevrolet Spark M300 blowing fuse problem
Often the simplest solutions are the best way to easily solve a bigger problem.
This repair deals with a (Chevrolet) Spark M300 car problem of my brother’s son. Normally I do not deal with cars or not even drive one. ( I have a drivers license but in my opinion driving a car only gives a lot of stress next to a lot of high Bills. Even just Parking costs money ). But it was about electronic circuitry and so it was something that got me interested.
The situation was a single 10A fuse that kept blowing up in his son’s car. But not immediately and sometimes not even for a couple weeks and for completely unknown reasons.
Above photo showed the Spark M300 fusebox.
My brother was able to solve this annoying problem successfully after I gave him some advise.
And in this short article I will present his product that proved to be a great help and solved his problem. This testing tool likely may also be of good use to some other readers too! No matter what car you have. (All cars have fuse boxes!)
Because the fuse kept blowing up and exactly the same happened when he used a 5A 32V fuse, It seemed that the over-current was something that only occurred at certain short times, so the average current likely was lower than 5A in general.
After searching for the cause we ruled out that it was the sealing light that caused the short circuit. And neither it was any of the door contacts or the inside trunklight. And we observed that the led indicator on the dashboard was always on when the 10A fuse was defect. And in that case the sealing light and the door contact indicator didn’t work of course.
And it seemed that also the safety belts had something to do with this shorting fuse. But it was still unclear what caused the fuse to burn. But of course it had to be a current higher than 10A.
To better explain the function of the fuse in the Spark M300 circuit, here follows one of the only two circuits we were able to obtain from official sources. The F1DA Fuse is the problem fuse in this repair.
The line (wire) 62 in the top that leaves the RD/D-BU 840 wire to the left direction goes to another circuit that connects to the Airbags. E36AH is the sealing light that activates when the car doors open or when the owner manually activates this light. X51A is the Dashboard panel, B69 is the switch that warns when the trunk is not closed yet. And E33 is the inside trunk light.
Because we didn’t want to keep replacing fuses over and over again, I advised my brother to use a large car light bulb of about 12V 5A with a 10A fuse in series. That way the fuse would be safe in case there was another momentary short circuit AND it would be clearly noticable by the lighting up of the light bulb. My brother found a small 55 Watt 12V Halogen Car bulb that he fitted in a small plastic bucked with on top a switch to be able to deactivate the light in the circuit (because these light bulbs can become quite hot in seconds).
And he used the old defect fuse to attach the test tool to the fuse box by simply plugging it in.
The above circuit is our TEST TOOL.
And previous photos gave a good impression of this great Test Tool that really helped in finding the problem. It turned out that the car cables beneath the backseats sometimes short circuited to the car’s ground connection. And my brother now was able to isolate the wire bundle to prevent it from happening again. It may not look or cost much but it did the trick and that is all that counts! I think my brother Ruud did a very good job, I couldn’t have done any better!
And in case problems like this do become almost unsolvable I recently decided to buy a Mooshimeter that is able to datalog Current and Voltage (up to 10A at max 600V) simultaneous. So it also can measure Power, or do a Diode or Resistor measurement. This meter not only is capable to datalog over a period of time of over about 6 months on a 32GB micro SD card, but works also at a very precise 24 bit resolution. And with any Smartphone or Tablet that has Bluetooth (Version Android 4.3 and higher, or Iphone) over a distance of about 50 meters. And even speaks out loud any value measured if wanted. And also has a built in oscilloscope graph like function. And can be FW updated over Bluetooth and put to sleep with your Smartphone or Bluetooth tablet too. You simply reactivate the Mooshimeter by shortly connecting both the C (common) and Ohm inputs. It is sold with 3 good meter CatIII (600V) wires with extra separate crocodile clamps and a nice portable etui safety case. And the Mooshimeter itself apparently is housed in a transparent sturdy and compact waterproof housing. Seeing all Youtube videos about this great (Crowdfunded) product it is said to be even better than any expensive (and dated) Fluke Multimeter too!
Albert van Bemmelen, Weert, The Netherlands
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Note: You can read his previous repair article in the below link: