i have a '99 civic dx w/ a '99 ex vtec head along w/ the factory OBD2b or version 2. I purchased a OBD2b to OBD1 harness, and everything is running good. NO check eng. lights, etc. BUT only one thing is that night time when u have all ur lights on, they dim. if the rpm is below 3k it is dark and sometimes hard to see the road due to dimmed lights but once u go above 3k it brightens, and i was just wondering is this just me or is it a normal thing. PLEASE someone lmk. btw, my battery is 1 yr old, and i tested my alternator b4 i quit pep-boys n it was in great condition.

 

check your grounds.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2lua &raquo;</TD></TR><TR><TD CLASS="quote">check your grounds.</TD></TR></TABLE> which ground wires? the OBD2 to OBD1 harness is a direct plug and play. unless u mean my engine harness for the vtec head swap.

 

I believe he means your engine compartment grounds. i.e. Battery negative calbe, transmission ground strap, valve cover strap, and the ground strap on the thermostat case.

 

yes, you got at least 3 grounds for engine alone.

 

thanks guys, i'll check them out tomorrow morning and let u guys know how it goes. i checked the valve cover one recently, but as for the battery ground and the thermostat grounds i'll double check them. thanks again.

 

Do not forget the transmission ground.

 

damn, i've check all grounds n it still dims and brightens. i guess im not the only person, b/c one of my friend has a p28 also n he says his does it too.

 

Mine does it too. But by "all ur lights are on" what do you mean? When your headlights are on? Or when you have your maplight/domelight/headlights on?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlacoy82 &raquo;</TD></TR><TR><TD CLASS="quote">Mine does it too. But by "all ur lights are on" what do you mean? When your headlights are on? Or when you have your maplight/domelight/headlights on?</TD></TR></TABLE>
Headlights bro, just as if u're driving normally u know what i mean? w/out dome lights on and all doors closed n such. but does urs do it every time u're changing gears? is there some kind of way to fix this bright to dim light problem??

 

grounds and or alternator

 

must be alternator because it is rev related.

 

**** mines don't do that is probably ur alternator going bad or something

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Slammed92hbonN20 &raquo;</TD></TR><TR><TD CLASS="quote">**** mines don't do that is probably ur alternator going bad or something</TD></TR></TABLE> i guess, i mean my car is a '99 and its now about 6 yrs old and so is the Original alternator. But i tested the alternator not too long ago while it was doing the same problem and it was in good condition. i tested it myself at work, i was an installer at pepboys and that was basically all i did all day besides batteries, tires and oil changes.

 

what is the output reading when you tested the alternator?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snoochtodanooch &raquo;</TD></TR><TR><TD CLASS="quote">must be alternator because it is rev related. </TD></TR></TABLE>

my old civic did it horribly...fixed it with a new alt.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2lua &raquo;</TD></TR><TR><TD CLASS="quote">what is the output reading when you tested the alternator?</TD></TR></TABLE>
to tell u the truth i don't remember the exact readings, but i checked it along w/ another mechanic helping me. man i mind as well get a new alt. it doesn't hurt to get a new one. thanks for all the help u guys. i really appreciate it. and to R33civic, when u replaced ur alt. did it fix the problem completely? or did it still do it?

 

yes it fixed my problems completely, my alt. was original and it was like near 8 years old so it was about time for it to go out on me. But I only had it shortly before a chick ran into the back of my civic totalling it.
I think you can test the alt. yourself without paying someone to fix it, and track auto is the place that realized that my alt. was bad, they ran some machine on it. I think you can test the alt. by having the car running and then take off the positive terminal to the battery and the car should continue to run, a bad alt. would cause the car to stop because the alternator can't keep the battery charged.

 

ic ic ic kewl thanks bro for the help. later

 

also check you alternator belt too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ek9 ferio &raquo;</TD></TR><TR><TD CLASS="quote">
Headlights bro, just as if u're driving normally u know what i mean? w/out dome lights on and all doors closed n such. but does urs do it every time u're changing gears? is there some kind of way to fix this bright to dim light problem??</TD></TR></TABLE>

Yeah, any time I'm driving at night and I go to shift and my revs drop below like 2k my lights will dim, and once I get back above t hat they will get bright again. I mean, its not a HUGE difference, but they dim enough so that I just happened to notice it one night.

 

You can try to cut wire OBD1 wire A16 (alternator control) to remedy this problem.

 

I agree. Alternator problem. Why else would it brighten with rotation? The alternator is weak and needs the extra revs to build juice.

 

could also be the ELD.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snoochtodanooch &raquo;</TD></TR><TR><TD CLASS="quote">must be alternator because it is rev related. </TD></TR></TABLE>

yeah prob a sign of a weak alt.