check engine light on after HID installation

[ludikris]

Hi ,

I installed my HID conversion kit the other day, and I noticed when I went to go for a ride today, my check engine light was on. Now I installed them on saturday and didn't drive my car until today which is tuesday. The kit was just t a plug and play more or less, and the only thing i had to do was replace the fuses from 10 amps to 20 amps as it called for it in the directions. Now im not sure if it is just a coincidence that my light came on after the install, or if it was the install that caused it. Has this happened to anyone else. My care is a 98 passat 1.8T.

[zollaf]

i wouldnt have thought that what you did would bring the em light on, but you never know. a code read will tell you more. im a bit concerned about changing the fuses from 10 to 20 amps though. the cables are probably not thick enough to handle that current, and should anything go wrong, such as a short circuit, then instead of the fuse blowing safely, you may end up with a melted harness, or a small fire. vag fit a 10 amp fuse for a reason, and its never a good idea to uprate a fuse under any circumstances. theres a saying, 'deviate from standard at your peril'.

[ludikris]

ok so is it normal that the company would tell you to replace the fuse with a bigger one bc they said that a 10 amp one would not be able to handle the power of the HIDs

[cazyp]

ok so is it normal that the company would tell you to replace the fuse with a bigger one bc they said that a 10 amp one would not be able to handle the power of the HIDs

What kit did you use?
As said the wiring to the 10amp fuse will be of the thickness to handle 10amps (+ a safety margin) but that wire is now carrying 20amps with more resistance = heat = melting = fire.

Only ever done one kit and all the wiring was replaced.

[snapdragon]

The same fuses or even smaller. HID are only about 40w max, whereas halogens are 55W. A 20A fuse won't blow until ABOUT 260W at 13V.

[cazyp]

But don't HID require a massive ignition voltage..? (2kV if I remember correctly>?)

[ddave05]

I think people have the misconception that HID's draw more current than standard halogens due to their increased light output. This sometimes results in the harness melting or worse.

The best bet would be to put the standard fuse back in, or if anything, get a 5A fuse instead.

[martin1810]

Standar rule in electrics or electronics....Never fit a bigger fuse...as Zollaf says. The fuse fitted will have been calculated to match the thickness of the wires it is protecting.

[snapdragon]

But don't HID require a massive ignition voltage..? (2kV if I remember correctly>?)

Yes, but that's irrelevant. A camera flash uses 50,000 Volts but runs off 2x AA batteries.

The ignition voltage for hid is like a static shock you get from walking across nylon carpet and this ionises the gas so that it becomes conductive enough for the 90 volts they need for normal use.

The only important thing with respect to melting wires and fuses is current (Amps) and the HIDs run at about 3 Amps each so a fuse up to double this 5-10A would be plenty.

[zollaf]

the hids may draw less current than standard, but my concern is if something goes wrong, say a wire rubs and creates a short straight to earth. the 10 amp fuse will blow before the wire, but the 20 amp fuse may not, and the wire may melt before the fuse blows, as its only capable of handling just over 10 amps. this could result in the loss of the car. would the company telling the op to do this warrant a claim in this instance?

[cazyp]

Yes, but that's irrelevant. A camera flash uses 50,000 Volts but runs off 2x AA batteries.

The ignition voltage for hid is like a static shock you get from walking across nylon carpet and this ionises the gas so that it becomes conductive enough for the 90 volts they need for normal use.

The only important thing with respect to melting wires and fuses is current (Amps) and the HIDs run at about 3 Amps each so a fuse up to double this 5-10A would be plenty.

I see what you're saying, but each ballast that ignites the HID's has an initial draw of 15amps on ignition (hence the manufacturers suggestion of a replacement fuse of 20amps,) this then drops to around 3amps once ignitied but each will draw a further 15amps on ignition of the full beam when flashing people etc. My concern.. is the standard wiring up to an albeit brief draw of 15 amps without melting?