Mystery Current Draw

[96eb96]

I don't drive it much but noticed the battery runs down more than it should. When I charge the battery I notice my electronic charger would drop voltage for a second. Two days later after a full charge, the battery is down to 11.9V.

I heard a faint relay click that happens about every 30 sec, seems from inside the dash. Threw a clamp on meter on the positive lead, I notice there is an interval where it jumps to a 5Amp draw for like 5sec, then drops to about 25ma. This is in sync with the click.

There are lots of relays behind the dash (power saver, etc) but I'm wondering if anyone ever had this? I have to start pulling fuses. I don't see any lights go on, so it could potentially be any relay.

 

[Mbrooks420]

Pulling fuses and under hood relays will be the most fruitful place to start. Locate the circuit, then dig up a wiring diagram.

 

[96eb96]

I pulled the radio, moved some wires around and seems to have stopped. I had mice in there, going to have to inspect wiring.

 

[Mbrooks420]

Good luck. Keep at it and you’ll find it.

 

[CDW6212R]

If you do isolate it to a relay, replace it with a new one. More and more these trucks are going to have the relays slowly fail, the ones that are used a lot. Good luck and posts some pictures or at least the info on circuits that turn out to be the current draw. Others will find this and it should help them solve theirs quicker.

 

[96eb96]

If you do isolate it to a relay, replace it with a new one. More and more these trucks are going to have the relays slowly fail, the ones that are used a lot. Good luck and posts some pictures or at least the info on circuits that turn out to be the current draw. Others will find this and it should help them solve theirs quicker.

Yep, long ago I had weird no start on a Lincoln. Would crank, but not start. One small clue. The CEL would NOT come on when you turn the key, not so obvious. It was the PCM relay.

 

[donalds]

Just had a pcm relay go out the other day

 

[CDW6212R]

Great picture donalds, and I bet most of the high use relays look similar to that now after 20 years. I've only had one relay fail completely, it ran the battery down, the fog lights never shut off(I almost never used them either).

 

[donalds]

Even the new fords use these relays cheep at the junkyard
"Low mile relays" Lmao

 

[CDW6212R]

Have they used the 2nd gen relays again since then, in any newer Fords? I love the 90's relays the best, two sizes that are equal in reliability.

See below, I built an OEM relay box and used three small relays, one large, plus a stock flasher receptacle epoxied in place. That is mounted under my MC, for RH turn signal control etc.

 

[Mbrooks420]

I’ve never had a relay fail in any of my Fords. For the extreme environment they live in they stand up pretty well. Next time at the pick n pull I should grab two to throw in the glove box.

 

[CRowlett]

I don't drive it much but noticed the battery runs down more than it should. When I charge the battery I notice my electronic charger would drop voltage for a second. Two days later after a full charge, the battery is down to 11.9V.

I heard a faint relay click that happens about every 30 sec, seems from inside the dash. Threw a clamp on meter on the positive lead, I notice there is an interval where it jumps to a 5Amp draw for like 5sec, then drops to about 25ma. This is in sync with the click.

There are lots of relays behind the dash (power saver, etc) but I'm wondering if anyone ever had this? I have to start pulling fuses. I don't see any lights go on, so it could potentially be any relay.

Disconnect negative battery post and hook up a multimeter on amps. Pull each Circuit breaker and watch the draw. It is time consuming. Be patient and do hem all. That will isolate the problem. I have had this problem. It turns out that it was the GEM module. But you could have another problem but Fords have trouble with Gem modules and this is one of them