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View Full Version : Engine dies when headlamps turned on...HELP!


89Wrangler
11-14-2003, 01:51 AM
Seems to be getting worse now...was ready to go home tonight and the Wrangler decided it wanted to die at stops...would crank over but not start unless I turned off the headlamps!

Got it back to work and hooked up the VAT40 Battery/Alt tester...battery checked out ok..above 10 volts on two 200amp draw test...also voltage was staying above 14 bolts at the battery when it would start to die when the headlamps were turned on....and it's not just the head lamps as you can get it to do this when turning on the radio and amp (amp pos is wired directly to the battery but the ground is to the floor board)...does not die when the elec fan kicks in (because it is wired (pos. and neg.) directly to the battery)...

There is a factory ground strap to the engine and firewall..but had to but a butt connector on it as it was broken intwo...Resistance in it?...will have to check that.

I also wired another ground from the battery to the engine valve cover stud....only thing I did not do was hook up a ground from the firewall to the battery...where's the stock one located?? Engine mount??

Also could have some resistance at the positive side..maybe fuseable links?...what about engine ground inside the vehicle and location?....

Anyone have this problem and figure it out....give me some ideas guys as the Wrangler is still at work as they let me drive home a company vehicle :)

I also check the Alt output under load which was 40 amps...which is what it is rated at...my 135 amp unit will be here tomorrow :) Also got a 2 guage upgrade charge (Welder) cable.

Oh...also bit of info...as I was saying it has gotten worse...when the elec fan would kick in it would also kill the engine when the head lamps were on...but this was because the fan ground was at the body and not connected directlly to the battery...hmmmm?


Thanks for any help guys!

Ken

chiso93yj
11-14-2003, 03:36 AM
voltage regulator, alternator, battery. check in reverse order as i have listed...

89Wrangler
11-14-2003, 12:01 PM
-=- originally posted by chiso93yj -=-
voltage regulator, alternator, battery. check in reverse order as i have listed...

All the above check out fine...battery is an oversize unit at 750 cca and is new....

Was thinking about it last night while sleeping...I fix a lot of cars in my sleep ;)

Voltage drop problem....I think if I install a new ground from the battery to the body that will fix it...also going to replace the ground strap from the body to the engine as well...both will be 2 guage to match the new alt charge cable with the new alt...hope I get the new alt today :)

Otherwise it's got to be a voltage drop in the positive side of the system.

Ken