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Parasitic Power Draw, Narrowed Down to Fuse 9 and This Shiny Thing?

GraniteCow

NAXJA Forum User
Location
USA
The battery is dying in the 96 XJ I just bought and my multimeter measures 1 amp at first, then settles down to about 350mA (measuring at the battery) with the ignition off. Unplugging fuse 9 under the dash drops current draw to about 10mA, and unplugging this round 3 prong flasher-looking thing drops it to about 30mA. It’s attached to the relay block under the dash. Any idea what might be causing this, what this round plug thingy does, or what to test next? Also the instrument cluster doesn’t light up with the headlights, I’m assuming it’s unrelated but :wantyou:
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Does it get hot ?
That should be the "thing" that controls the halo light around the Ing switch.

Also,door jam light switches and even headlight, dash lights, dimmer switch in that circuit
 
Last edited:
Does it get hot ?
That should be the "thing" that controls the halo light around the Ing switch.

Also,door jam light switches and even headlight, dash lights, dimmer switch in that circuit

It gets pretty warm.

So I unplugged the headlight switch and this stops the drain as well. The dimmer doesn’t work and the left blinker indicator was lighting up a bit when the headlights were on so I’m wondering if it’s the switch. I have one coming today so I should know soon.
 
I came here today with the same problem on my 92 XJ. After taking apart the hatch and disconnecting the dome switch, dropping both domes (Breaking one clip washer), taking apart the dash and removing the radio I check the Glove Box as mentioned here and it went away.


Thanks


I have a FSM with the dome circuit page here:
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https://ibb.co/gv8cjcX
 
Update: It’s getting weirder

When dimmer (headlight switch) is turned all the way counter-clockwise, the draw is there. When it’s turned clockwise, it goes away. When I disconnect the ground wire to the headlight switch, the draw goes away (there is a 12v potential between switch body and ground, but only when turned 100% counter-clockwise).

I also noticed that the fuse for the dash lights (aka dimmer circuit) was missing, so I put it in. Now both the turn signals and driving lights don’t work, and the dash lights only work when I hold the headlight switch in an “in-between” position between no lights and driving lights. I can hear the dash light relay click when I jiggle it here.

There is no clicking when I use the turn signal, but the hazards still work as normal.

I have now discovered why this Jeep was for sale.

Any ideas? I’m pulling my hair out here.

Btw, unplugging glove box light does not affect it.
 
I'd start with replacing the headlight switch. Then the signal(multipurpose) switch. I've also had one of the relays, red or blue,I don't remember go bad and cause a blinker problem.
 
I'd start with replacing the headlight switch. Then the signal(multipurpose) switch. I've also had one of the relays, red or blue,I don't remember go bad and cause a blinker problem.

If I recall correctly the red relays are timer relays for use with defrost circuits in rear glass.
 
If I recall correctly the red relays are timer relays for use with defrost circuits in rear glass.

Right you are, IIRC it was a blue one, But then I think it was traced to a wire being corroded in the fuse block and the relay was fine.--In Mine---
 
Another update:

I have another 96 (parts vehicle) with working electronics. I measured the current draw with the dimmer turned full counter clockwise and it’s the same! About 350mA, goes down to 30mA with the switch turned clockwise. Maybe it’s just a bad design?

I tested all 4 relays and the turn signal switch by swapping them into the parts heep and they work fine. I tried with two different headlight switches and the results are the same.

Currently, none of the gages or dash lights work in the Jeep I’m trying to fix. It’s been intermittent though, and I haven’t found a bad ground or connection. Could something on the engine side of the firewall cause these issues? I’m at the point where I’m considering removing the dash and swapping in all of the wiring and electronics from the parts Jeep that’s actually pretty complete and that I planned on selling. The Jeep I’m fixing runs though, the parts Jeep blew a head gasket. All I can think of at this point is corroded connection or shorted wire somewhere behind the dash.

Any suggestions before I swap the entire dash wiring harness and switches?
 
Edit: the ignition switch doesn’t light up now either, and jiggling the headlight switch does not turn on the dash lights, but I can hear the relay clicking
 
According to my testing several years ago, a Renix XJ (89) has about
a 14mA draw normally. An HO (96) draws about 7mA.

Auto mfgs are required to design vehicles so the "normal" battery drain
is such that the car will still start after 30 days of sitting, such as in an
airport long-term parking lot.

I have found that car radios, especially aftermarket, will sometimes
start using more memory current over time. Try disconnecting the
radio and see if that lessens the drain...
 
RE: the intermittent gauges/instrument lights - have you given the "bulkhead" connector (under brake booster, under-dash fuse block connects to it) a really good going over for corroding/corrosion-separated wires?
 
The under dash fuse block is pretty corroded tbh. I pulled off the bulkhead and cleaned it really well (lots of tar-like stuff like on the terminals) but there was no change. I did narrow down the parasitic power draw in the parts Jeep to the ABS system, and the one I’m fixing doesn’t have ABS so this isn’t an issue. The harness from the parts Jeep is in really good condition so I’m just going to swap them.

On the plus side, I was able to clean out some 20 year old French fries from inside the heater box and discovered the heater core was leaking when I pulled the dash! I have a new heater core coming today. I also got gung-ho with the engine cleaner and spruced up all the grounds I could find. Oh, the joys of buying old Jeeps on Craigslist!
 
Update for anyone with the same issues:
1) Up to 500mA power draw (on mine at least) is normal with the headlight switch turned fully counterclockwise. This turns on all interior lights.
2) I had to replace the dash harness with one from a junkyard. Problem solved.
 
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