HID causing unsteady voltage w/ relay harness

phanpride

Original poster
Member
Mar 10, 2012
16
I am sorry if this question or dilemma has already been addressed, I've looked through the forum but couldn't quite find a specific answer.

Isuzu Ascender 2006 LS

The Problem:
With the relay harness the voltage meter of the dash is unsteady sometimes below the quarter mark and sometimes right at 14, when it is below or the near the quarter mark the dash and meters shuts down when I turn on the HID's, when they are turned off all power returns to normal. I have also mounted the positive side onto the fuse box next to the battery but seems to have the same problem. If I used the HID's w/o the relay harness there isn't any problems yet.

I recently installed HID's from HIDMASTERS a few days ago and I also bought a relay harness and did not do the capacitor mod. The positive side of the relay harness is mounted directly to the battery and the ground is mounted on the side of the car.

Any clue as of what I need to do?

Thank YOu for your time
 

Me007gold

Member
Nov 20, 2011
1,106
phanpride said:
I am sorry if this question or dilemma has already been addressed, I've looked through the forum but couldn't quite find a specific answer.

Isuzu Ascender 2006 LS

The Problem:
With the relay harness the voltage meter of the dash is unsteady sometimes below the quarter mark and sometimes right at 14, when it is below or the near the quarter mark the dash and meters shuts down when I turn on the HID's, when they are turned off all power returns to normal. I have also mounted the positive side onto the fuse box next to the battery but seems to have the same problem. If I used the HID's w/o the relay harness there isn't any problems yet.

I recently installed HID's from HIDMASTERS a few days ago and I also bought a relay harness and did not do the capacitor mod. The positive side of the relay harness is mounted directly to the battery and the ground is mounted on the side of the car.

Any clue as of what I need to do?

Thank YOu for your time


The Capacitor mod is done to provide full power to your drl's. Something still needs to be done about the DRL's wither you do the cap mod or use a DRL Killer. Dont have any advice about your other problem though.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The voltmeter on the dash isn't a "real" meter in that the measurement is done near the meter. The measurement is actually done in the PCM, which is bolted to the driver's side of the intake manifold. So a bad reading that fluctuates is more a clue that the PCM is being influenced, and sending a data message to the gauge cluster that's got bad data in it. Think of your gauge cluster as if it's a PC peripheral connected by a USB cable. All it can do is display things that are sent to it by data packets.

Get a real meter like the $2.99 ones on sale at Harbor Freight, and you will know for sure that your battery is OK and the voltage going to the HID unit is fine.

HIDs, especially low cost ones and double especially ones that are buzzing on and off if you don't have a DRL killer, radiate a HUGE amount of electrical noise on their wiring. This electrical noise can couple (jump across) into all sorts of other wiring in the vehicle and cause confusion. So if your ground wire to the fender, for instance, goes too close (within 3-4") of any wiring that also goes to the PCM, the PCM can freak out. It could also cause your engine to shut off. So as a first experiment, move your HID wiring so it doesn't go near any PCM wiring. Change the HID ground to go to the battery instead of the fender. And for pity's sake get a DRL killer of some sort in there. The way our DRL function works is for the headlights to be turned on and off around 200 times a second, faster than the eye can notice, at about 70% on time, and 30% off time. This control (called PWM if you want to Google for that - pulse width modulation) is too fast and potentially destructive to the high voltage circuits in a HID unit. HID lights have to be full on if they're on at all.

I'm actually in the middle of a design project at work where radiated noise (400V, 200A pulses only 10-20 nanoseconds wide) can magnetize any steel within a couple of inches of the circuits. We went to great pains to replace steel with aluminum or plastic, and were still losing a few percent of our energy to some mystery place. After 2-3 days of head scratching, we realized we had some unrelated coax cables within the danger zone, and the COLLARS of the BNC cables were magnetic (even though all the guts of the cables were copper or Teflon). Don't even get me going on how we found some 60 Hz interference was caused by the rotating parts of our AC cooling fans, 4" from the pulsed source. That took a week to be suspicious of permanent magnets built into the hubs of darned cooling fans. :mad: :hissyfit:

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