Headlight Harness Upgrade - $23

[65-f100]

Hey guys - new to the group and have already learned alot. Wanted to share some info. that I found that I had not seen posted. Being mainly from the hot rod side of things - I checked with Painless wiring to see if they had any upgrades for our trucks. They sell a headlight relay harness so that all 4 lights come on. The best part - it was $23. They sell through Autozone so they should be available all over. I installed mine this weekend and it works great. Very easy to install. Thought you might enjoy this as the other ones I've seen were a lot more expensive.

[S\W Off Road]

Good for you! Hate to tell you this but you just bought a $0.10 diode that gets spliced between the high and low beams. I learnd the hard way too on the first time around.

[a5150nut]

$0.10 diode ?? I used a relay. Silly me.....

[65-f100]

This one is not a diode - it's a relay. And yes - you're right it does splice between the low and high beams and draws power straight from the battery or you can pull power from the alt. The point is that it makes all 4 lights come on and now I can see better. Still seems like a pretty good deal to me.

[Kennedy]

Relieving the undersized factory wiring setup is still the best way to go. Not to mention relieving the load on the headlamp switch...

[gmctd]

Are you sure about that diode, S\W Offroad?
No matter the price, a silicon diode will drop about three volts when forward biased, germanium and schottky somewhat less.
Any drop would not be good at the headlites.

Also, how's your 'recovered' FSD working out? You were the first (other than me ;) ) to 'trip' to what I was suggesting, so I've been wondering.
Guess no news is good news?

[S\W Off Road]

Originally posted by gmctd:
Are you sure about that diode, S\W Offroad?
No matter the price, a silicon diode will drop about three volts when forward biased, germanium and schottky somewhat less.
Any drop would not be good at the headlites.

Also, how's your 'recovered' FSD working out? You were the first (other than me ;) ) to 'trip' to what I was suggesting, so I've been wondering.
Guess no news is good news? I was going by what kennedy has on his web page

Four lamp high beams is made possible through a diode that is plugged into a connector, conveniently located in the harness.

This is how I found out. I also bought a 4 highbeam light kit and paid to much for it before I found this out. I bought mine from Pep Boy's for about $9.00 and it isent even a relay so I got even less.

My FSD started acting up again and it seemed that everyone I tryed (4 in all) were messing up. I found my battery cable lose and that seems to have stopped my problems. I coneceted back to the FSD on the injector pump and it even works :confused:

[Kennedy]

Originally posted by gmctd:
Are you sure about that diode, S\W Offroad?
No matter the price, a silicon diode will drop about three volts when forward biased, germanium and schottky somewhat less.
Any drop would not be good at the headlites.

Good point!

BTW, we only use the diode for the control side of the relays...

[gmctd]

As I suspected, John...

On another note -
To anyone installing this or any other relay-switched device into the PCM-equipped trucks, make sure a 'commutating diode' is placed across the coil terminals, 'banded' end on the positive (+) supply terminal.
This prevents the 3000v and higher negative spike from damaging the electronics system.

Most relays in 'computerized' vehicles since '80s have this diode built-in.
Others get the diode as part of the wiring harness.
That's a diode in the a\c compressor connector.
The factory quad high beam option in my truck has the diode.

The diagrams on 'Euro' relays depict the diode as a small rectangle wired to each side of the coil.
Which means the relay coil connections are 'polarity specific', if you're adding in a relay.

Any quality harness should conform, but check any assembled harness(es) from Autozone, Pep Boys, etc, to be sure.

S\W Off Road - Don't 'lose' those FSD modules - most do not actually fail beyond recovery.

[ 03-08-2004, 07:03 PM: Message edited by: gmctd ]

[65-f100]

I agree with you Kennedy that your set-up is probably best because of the upgraded wiring, but for those of us on a budget (aren't we all??) - the relay is definitely an improvement over the stock set-up. This way I can save some $ and buy some of your performance upgrades!

[tom.mcinerney]

Thanks for mentioning [and describing installation of] the 'commutating diodes, J.D. I'll have to get a few.
I recall Charlie Peterson reported dismantling a liftpump that crapped out in cold-weather/gelling conditions earlier this winter. I believe he said the points were burnt. That's also an inductive load, intermittent. Do you suppose 1.) that a diode is part of the LP internal circuit(may explain the fact that LP is polarized) , or 2.) that a diode would be good to fit in its harness?

[gmctd]

Dunno, Tom - I've only seen the electronic version, which is transistor driven, internally.

Some type of suppression would be needed, over and above the diode for reverse emf suppression, because of the break-current.

If a mechanical-points type had the diode, it would be just as polarity specific as the electronic version.

I may have to nab several next boneyard event, for some inquisitive r&d.

p.s. - What was the outcome on your 4L80 hemorrhaging?

[ 03-09-2004, 03:20 AM: Message edited by: gmctd ]

[tom.mcinerney]

4L80 & scope-recapping still on backburner; plan to revert stock heater plumbing....

[gmctd]

When my tig comes in - first the charge air cooler, then some appropriately fashioned and positioned nubs on the t-stat manifold.
I gots to know! :cool:

Problem is the sensors - Isspro would not sell probes separately.
I had to buy two of each gage to get the in\out probe pairs for my truck.
I am gage poor, as it were. Guess two more won't break me.
Maybe the Easter Bunny will be kind, this year. ;)

FYI The AC\Delco\Delphi lift pumps are transistorized - scr, trigger diode - and input protected for polarity.
Power and ground reversal have no effect on the circuit.

[tom.mcinerney]

J.D.:
I've never measured for'd volt drop of a diode in a circuit. But your post above, (3/08/04, 10:42 a.m.) activated my memory-checking.
>>"No matter the price, a silicon diode will drop about three volts when forward biased, germanium and schottky somewhat less."
I respectfully submit, for comparison:
"However, germanium diodes have the advantage of an intrinsically low forward voltage drop, typically 0.3 volts; this low forward voltage drop results in a low power loss and more efficient diode, making it superior in many ways to the silicon diode. A silicon diode forward voltage drop, by comparison, is typically 0.7 volts." From <http://www.americanmicrosemi.com/tutorials/germaniumdiodes.htm>.
The contention in your post, that a high-power circuit like headlamps would suffer from an inserted diode is valid, but is the number(3)?
If you could explain, i'll listen; or edit, and i'll erase this!

[gmctd]

Your post is valid in content, Tom, as is the question.
So, no need for any deletions. smile.gif

All diodes are not created equal.

Germanium diodes are mostly used in signal ciruits, micro-amp to 100ma current ratings.
Silicon signal diodes are also available.
A 0.3v germanium choice over 0.7v silicon is used where the criteria is signal sensitivity and quality (1N34A).
0.7v silicon is used where criteria is hi-voltage gating (1N914B, 1N4148, etc).

The silicon rectifier diodes commonly avilable at *adio *hack are usually in the range of 1.2v to 3.0v forward drop, and a few of the numbers in those 100\98cents packages are in the .7v class.

1N4000 series are 1.1v drop at 1 amp.
1N1197 is 2.35v at 18 amp.
1N1134 is 8.0v at 0.003 amp
1N1146 is 60v drop at 0.050 amp.
1N3061 is 125v drop at 0.1 amp

Silicon forward voltage drop is usually determined by voltage and current ratings.

Schottky diodes can drop as low as .38v in 1000amp range, but are limited to low voltage applications, less than 200v priv.

My statement was intended generic in spec but specific in scope, indicating a simple diode "gate" would be a poor choice for quad hi-beam connection, were anyone considering it.

Hope this is helpful.

[tom.mcinerney]

Wow, how 'bout that! Once again you've opened a sizeable door of my ignorance.
I'm going to see about getting some in the 3V-1A range to use as dimmers when i do gages....
Thanks, again, J.D.

[gmctd]

A suggestion - would be variable dimmer if diodes in series were switched into the ckt, one or more at at time.

A string of 1N4004's, commonly available, are 1.2v drop at 1amp rated

1N4865 are 2.4v drop at 1.25a
1N4866 are 3.6v
1N4877 are 4.8v
1N4878 are 8.4v
1n4869 are 12.0v

Note: slight variances in parameter values are due to oem listing peak and average values without distinction.
'Typical' would best describe numerical values.

[ 03-15-2004, 08:53 AM: Message edited by: gmctd ]

[S\W Off Road]

Can I use one to dim my SES light? :D

P.S. I Installed a light booster from suvlights that uses two relays and I really does make them brighter, and cheap too! :D

[whatnot]

gmctd,
now that you answered tom mac 95's question, I have one. The 3000v spike you mentioned would be caused by the relay coil? If so, couldn't you just use a solid state relay instead?

[gmctd]

Correct on both accounts, Whatnot.
However, solid state relays are polarity sensitive on input and output side, requiring high-voltage transient suppression on the output if connected to an inductive source.

The output drive transistor is turned off, but is still in the load circuit, where the relay contacts open the load circuit.

And, being solid state, forward-junction voltage drop is still an issue.

Control voltage is in 3 to 30 volt range.
Output is 60vdc rated at 3amps, 5amps, 10 amps and 25 amps

Opto22 is a good source, and most brands\types can be found at a local electronic surplus store.

I have considered using an Opto22 in the lift pump circuit, since it would be powering a solid-state motor-drive circuit, but have not R&D'ed it fully.