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Installation Instructions for Time-Delay Relay

     on a H4/9007 HID Headlight System


These instructions detail the installation of the Time-Delay Relay on a H4/9007 HID Headlight System, as this is the most popular use of this relay. Installing this relay on other systems, or using it to control other devices, is very similar, but if you have any questions, please feel free to contact me.

What's Included

  • Time-Delay Relay unit
  • 5  0.25" spade terminals

What You Need

  • Wire for wire harness
  • Wire stripper
  • Crimping tool (or pliers)
  • Inline fuse(s)
  • HID ballasts

Headlight Wiring

Before you start hacking on your vehicle's wiring, you should probably plan out exactly how you want to install your Time-Delay Relay, and the rest of your bixenon system. The first step is to determine how your vehicle's headlights are already wired. If you can get a diagram from your vehicle's service manual, or perhaps a Haynes or Chilton book, that would be best, but if not, you can still figure it out pretty easily.

Below is a diagram of an example positive-switched system in stock form, from a 1994 Honda Civic.

Stock Headlights
Stock Headlights

As you can see in this diagram, the combination switch's dimmer function only allows current to flow to either the high-beams or the low-beams, but never both (unless the passing switch is held on). Wires from this switch go to the fuse box, and then four separate wires go to each headlight bulb (two to each side). This delivers power to the bulbs, which are then connected to ground, somewhere on the car's frame.

Now here is a diagram of this same system, but modified with bixenon HIDs, and using the Time-Delay Relay. This diagram shows a single TDR being used for both HID ballasts, but if you prefer to use two TDRs for maximum redundancy, it should be simple to see how to hook them up.

Modified Headlights
Modified Headlights with Single TDR

Here, the halogen headlight bulbs are gone, and replaced by HID bulbs and ballasts. I also illustrated this system with my bixenon solenoid controllers, but if you're not using Bosch 3-wire projectors, then this doesn't apply to you. As you can see here, the four headlight fuses in the fuse box no longer power the system. Instead, the high-beam wires are connected to the bixenon solenoids (or controllers), and the Time-Delay Relay is connected to one set of high and low beam wires.

The HID ballasts' positive terminals are connected to the battery, through three fuses. Each ballast has one 20A fuse, and the two then share a 30A fuse at the battery, which also protects the Time-Delay Relay. The secondary 20A fuses are important, because with them, if one ballast fails and blows a fuse, it's most likely to blow the 20A fuse nearest it, leaving the other ballast powered on so that you still have one working headlight. The 30A fuse protects the whole system, including the remote possibility of a defective TDR.

Modified Headlights
Modified Headlights with Dual TDRs

This diagram shows the same system, but with dual TDR relays instead, one for each headlight. This provides the maximum in redundancy and reliability. Each ballast has its own TDR, and each TDR, along with its associated ballast, is protected by a 20A inline fuse. This system requires two TDRs instead of one, but only needs two inline fuses instead of three.

The Time-Delay Relay is designed for low-side switching, so the ground/negative terminals of the HID ballasts are connected to the "ballast" terminal of the TDR, which then connects and disconnects them to and from ground. Finally, the TDR's ground terminal is connected to a suitable ground, perhaps one which one of the headlights used.

Now that you understand how the wiring will work, you just need to decide where to mount your Time-Delay Relay, along with your other HID components if they aren't already installed. You should probably install it someplace where it won't be hard to route one set of low and high-beam wires to it. The TDR case has two mounting ears with holes, and can be mounted on sheet metal using self-tapping screws.

Wiring Instructions

  1. Before modifying any wiring, disconnect the battery on your vehicle, so that there is no power applied to the circuits.

  2. After installing your Time-Delay Relay where you want it, cut off one of your H4/9007 headlight sockets, run these wires to your TDR, strip the wires and install spade terminals. Then connect them to the input terminals "1" and "2" (high and low beam wires are interchangeable here). Also splice a length of wire from the high-beam wire and connect this to your bixenon solenoid (or to the + connector on the bixenon solenoid controllers if you're using them).

  3. Next, cut a length of wire long enough to go from the Time-Delay Relay to your battery (or whereever you prefer to get power from). Be sure to install an inline 30A fuse, connect one end to your battery, and connect the other end to the TDR's "+12" terminal with a spade terminal. You may want to use red wire for this.

  4. Cut two lengths of wire long enough to go from the Time-Delay Relay to each headlight's HID ballast. Splice these wires to the wire you just connected to the TDR's "+12" terminal, and then connect the other ends to the positive terminal of whatever connector you need for the ballasts (frequently a 9004-type connector), installing an inline 20A fuse on each wire. You may want to use red wire for these two lengths of wire as well.

  5. Cut two lengths of wire the same length as the previous two, to go from the Time-Delay Relay to each ballast. Splice them together, and connect the joined end to the "L" terminal on the TDR with a spade terminal. Connect the other ends to the negative terminal of whatever connector you used for the ballasts. You may want to use black wire for this.

  6. Find a suitable ground wire, such as the one that was connected to your H4/9007 headlight socket, or connect one to a clean spot on the chassis with a ring terminal and screw or bolt. Connect this to the TDR's "G" terminal using a spade terminal, and splice additional wires from here to the bixenon solenoids (or - connectors of controllers).

  7. It's best to use wire of at least 16 gauge (AWG) size or larger from the battery to the ballasts, from the ballasts to the Time-Delay Relay, and from the TDR to ground. The wires connected to the "+12" and "1" and "2" terminals can be smaller, as they conduct much less current.

Time-Delay Relay Connections
Time-Delay Relay Connections

Testing and Adjustment

Now that your system is installed, you can turn it on and try it out.

First, you should determine if your triggers are positive or negative, and set the polarity switch on the TDR accordingly. If your trigger is positive (goes to +12V when "on"), then set the switch off. If your trigger is negative, then set it "on". If you don't know, you can try both settings, as the TDR simply won't turn on if the setting is wrong.

Your lights should come on immediately when either your low or high beams are on. If one or both of them do not come on, try disconnecting the wire from the "L" terminal of the Time-Delay Relay, and connecting this directly to a suitable ground. If the ballasts do not come on, check the fuses and then the wiring to make sure everything is wired correctly. If the ballasts do come on, check the wiring, but the TDR may be malfunctioning.

If everything looks fine, try switching between high and low beams. The HID lights should remain on, without any flickering.

Time-Delay Relay Adjustments
Time-Delay Relay Adjustments

Turn off the lights. By default, the Time-Delay Relay is shipped with the minimum turn-off time of 1/4 second. Your lights should turn off about 1/4 second after turning off the headlight switch. If you wish to increase this time, remove the TDR from its mounting location, while keeping the electrical connections intact, and use a very small flat-blade screwdriver to turn the adjustment knob marked "O" on the backside clockwise. These knobs have 20 full turns of adjustment, so it may take many turns to reach the desired delay time.

If you wish to add a delay before the lights turn on, adjust the knob marked "I" on the backside clockwise. Experiment with turning the lights on and off, and adjust these knobs, until you reach the desired turn-on and turn-off delays, then replace the TDR in its normal mounting location.