Point of order: the 10A range is too high for this measurement. You only use the high range first in case you've done something wrong and created a short. Once you have it set up properly (getting 0 - 0.01 A, or 10 mA) you can gt to the mA range for a more accurate reading. Also, in my meter (Fluke 187) both current ranges are fused - there are 2 fuses inside per owner's manual, a big one for the 10A range and a small for mA. HTH
fj62 dome light circuit parasitic draw
- Thread starter Devils Paw 80
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Sorry it took a while to see this. I haven't had time, but should shortly(pun intended). I'm also having something "weird" happening with a CB radio I have installed. I have the CB radio hooked up directly to the battery via the auxiliary fuse box. When I have the CB radio on and the vehicle is running and I hit the horn, the CB radio's power meter pegs as if though I were transmitting!? Wth?
Yeah, that's good info on the behavior of the 60 Carb Cooling fan circuit...it does indeed run off the same 'Dome' fuse circuit on the 60 as the Dome lights...
It makes me wonder, when you describe the dance you have to do in order to get the system to behave in a manner so that you could measure the current leak, if the timer (in the 'computer') might run off some sort of capacitor doo-dad, that only gets a charge when the ignition switch gets turned on...dunno...
I took another look at the wiring diagram for the 62 and didn't see a Carb Cooling fan included in the diagram...maybe the 62s with the 3F have one, but I wouldn't expect the 3FE to have a Carb Cooling Fan (no carb!).
True...
...not being familiar with the exact model or how it takes the current measurements, I guess I'm just trying to first do no additional harm in providing suggestions...and leaving it up to the operator to be familiar with the particular model they are using.
JawJa, can you think of a better strategy/approach to narrowing down the location of the current leak on the Dome circuit? I'm being cautious in my recommendations since the circuits behind the Dome fuse are not switched through the Ignition switch...so something as simple as opening a vehicle door with the DIMM installed to the wrong setting might fry the meter...
Maybe it is better to start at the non-battery side of the Dome fuse and work out towards ground(s)? I've been suggesting to 89GASHOG to start at the Door switches and work back towards the Dome fuse...with the line of thinking of working first the far side of a component, then move on back towards the Dome fuse component by component until he sees a current.
I don't think using the Continuity feature on any given DIMM will help, since it autoranges to up to say ~100 Ohms so that it can read it's own signal. If there was a way to set the current output to the value of the current leak, that approach might work...but that would have to be some kind of fancy DIMM...
What about using 2 DIMMS somehow?
Just trying to think outside the box...
- Thread starter
- #65
62's do have them. At least, mine does. Rarely comes on, only time I recall is on road trips, when making a pit stop after an uphill grade. Here is an explanation of their purpose with the EFI, from another MUD thread:
"It blows air over the intake/exhaust manifold area to stop the injectors/fuel rail from getting too hot when you turn the engine off and there is no air-flow.
As mentioned, lots of non-cross flow I6 engines used them. Like the Ford 4.9L I6. Ford later dropped the fan and went to a much higher fuel pressure to combat fuel boiling."
I'm thinking that either the aux fuse box or the CB radio circuit would be the most probable suspect in your case...
It might be that the horn speakers are a similar frequency to the CB? I have a set of stereo speakers that pick up/feedback everytime a cop car passes by...
Huh. I'll go back and take another look at that wiring diagram then. Do you happen to know if it runs off the Dome fuse circuit?
That was a relaxng vacation...
Indeed the 3FE 62s have a "cooling fan". It surprised me too. I guess it's because everyone calls it a "carb" cooling fan, where in actuality it's a "manifold cooling fan".
I can't find any documentation of it in wiring schematic for the 60 either.
Indeed the 3FE 62s have a "cooling fan". It surprised me too. I guess it's because everyone calls it a "carb" cooling fan, where in actuality it's a "manifold cooling fan".
I can't find any documentation of it in wiring schematic for the 60 either.
Well, I've gone just about cross-eyed staring at the wiring diagram that I think is the correct one for the FJ62...still don't see it there...
I'm looking at the one in the '1984 chassis-body' FSM from this website:
https://forum.ih8mud.com/threads/fsms.743084/
Well, easy enough to rule that sucker out of the Parasitic Drain Equation. ... Unplug the box. . ( behind the passenger's floor kick panel. It's labeled "cooling fan relay" or something like that.
Here's the schematic for the 60.
You can see that right after the Dome fuse (which is the 5A fuse that is unlabeled...probably a printing error), the RB (Red with Black stripe) wire splits...and one leads out to the Cooling Fan Relay.
The Cooling Fan Motor turns on when the Cooling Fan Motor Relay closes.
The Cooling Fan Motor Relay is controlled by the Cooling Fan Relay.
The Cooling Fan Relay is controlled by the temperature dependent grounding of the Manifold Temperature Sensor.
So a short to ground in the Cooling Fan Relay would then be the most probable culprit in this system because it is the one that is 'seeing' constant 12V+ from the battery (even with the Engine OFF and Key OUT of ignition).
You can see that right after the Dome fuse (which is the 5A fuse that is unlabeled...probably a printing error), the RB (Red with Black stripe) wire splits...and one leads out to the Cooling Fan Relay.
The Cooling Fan Motor turns on when the Cooling Fan Motor Relay closes.
The Cooling Fan Motor Relay is controlled by the Cooling Fan Relay.
The Cooling Fan Relay is controlled by the temperature dependent grounding of the Manifold Temperature Sensor.
So a short to ground in the Cooling Fan Relay would then be the most probable culprit in this system because it is the one that is 'seeing' constant 12V+ from the battery (even with the Engine OFF and Key OUT of ignition).
Agreed. If the circuit on the 62 is similar to the 60, then pulling the 'Cooling Fan Relay' and then rerunning the current measurement at the neg battery terminal should rule out the 'Cooling Fan Relay' as the culprit.
- Thread starter
- #74
I have FJ62 FSM. Cooling fan is on Engine circuit, so no dice. Edit: See below.
- Thread starter
- #75
Oh wait, maybe not. Dome circuit does show a line to radio and tape player, plus cooling fan (engine), whatever that means. Hmmm, I will try it...
There also might be a procedure in the FSM for testing that Cooling Fan Relay directly...to see if it is in proper working order...
- Thread starter
- #78
It's a hard copy. Don't think I can get a good photo of it..
I have it on pdf ..let me know which section and page and i'll give it a shot
Let's get some meter basics down - skip if you already know this. I am an EE/electronics designer with over 30 years in the biz, so this stuff is like breathing to me. 
Note 1: in DC V (volts) mode, the meter acts like a very high resistance ( an open switch or open circuit) in parallel to the circuit you are measuring. The meter is connected in parallel to the item under test (recall voltage across parallel loads is the same for all loads).
Note 2: In DC A ( or mA) current mode, the meter acts like a piece of wire - a short circuit (also called closed circuit or closed switch). This is why you never connect a meter in current mode across your battery! If you connected a wire across the battery what happens? Fire! To measure current, you "break" the conductor you want to measure the current in, and the meter goes in SERIES with the "break". An easy was to "break" a circuit is to pull the associated fuse.
Measuring current in the suspect circuit is only a start to pinpoint a leak. Recall in DC Voltmeter mode, the meter acts like a very high resistance in parallel with whatever the probes are touching. If you, for example, pull the fuse for a suspect circuit and put the voltmeter (in DC V mode) across the two terminals, and it measures 12 V, then there is a leak to ground somewhere that is much less resistance than the meter itself, by the voltage divider rule. If you measure 6V, for example, then the leak resistance is the same as the meter (in this case, I wouldn't worry too much as the meter input resistance is so high it wouldn't be a significant drain.) Typically if there is a leak or load you will measure 12V. If you get 0V, then there is no path to ground - no leak. Once you find the leaky circuit, you can switch meter mode (and probes) to DC A mode and again go across the removed fuse terminals (or opened wire) to measure the actual leakage current.
Now recall that even when off, things like stereo, clocks, and such still have a slight current draw which is normal. You may have to disconnect these things when troubleshooting to get them "out of the circuit". In the case of the dome light circuit, there are many paths to ground. On the drawing you will see, for example, 4 door switches in parallel so that if any one (or more) of them are closed, the light comes on. You have to use your head and the drawing to see what all is a possible path to ground. In the Toyota, the ground wires are routed to various points on the body and frame where they are screwed in. You may have to locate these and temporarily unscrew them one at a time to figure out where the problem is, which is usually a bad or incorrect connection. The FSMs have this info, and the schematics are drawn so that 12V is at the top and flow down to grounds at the bottom.
In every used vehicle I have ever owned, I find electrical things that were added, repaired, or modified in a crappy manner, with no heat shrink, twisted together with black or duct tape, and often connected WRONG. I always suspect this stuff first. For example, when I re-did my FJ60's trailer connector wiring recently, I found a horrendous rat's nest of bad connections that was done by retarded spider monkeys. I ripped it all out, repaired the stock wiring, and then installed a new wiring kit properly. Same with stereos and aux panels added by a PO - look upon that stuff with a jaundiced eye.
Hope this helps. If you were in the neighborhood I would come over and help, but all I can do is be a sage and a cheerleader on the internet. Keep at it in a methodical manner until you find the problem. Disconnect non-stock stuff. If you are SURE everything is correct and you still have a problem, then something you are SURE is correct is, in fact, incorrect. Good luck.
Note 1: in DC V (volts) mode, the meter acts like a very high resistance ( an open switch or open circuit) in parallel to the circuit you are measuring. The meter is connected in parallel to the item under test (recall voltage across parallel loads is the same for all loads).
Note 2: In DC A ( or mA) current mode, the meter acts like a piece of wire - a short circuit (also called closed circuit or closed switch). This is why you never connect a meter in current mode across your battery! If you connected a wire across the battery what happens? Fire! To measure current, you "break" the conductor you want to measure the current in, and the meter goes in SERIES with the "break". An easy was to "break" a circuit is to pull the associated fuse.
Measuring current in the suspect circuit is only a start to pinpoint a leak. Recall in DC Voltmeter mode, the meter acts like a very high resistance in parallel with whatever the probes are touching. If you, for example, pull the fuse for a suspect circuit and put the voltmeter (in DC V mode) across the two terminals, and it measures 12 V, then there is a leak to ground somewhere that is much less resistance than the meter itself, by the voltage divider rule. If you measure 6V, for example, then the leak resistance is the same as the meter (in this case, I wouldn't worry too much as the meter input resistance is so high it wouldn't be a significant drain.) Typically if there is a leak or load you will measure 12V. If you get 0V, then there is no path to ground - no leak. Once you find the leaky circuit, you can switch meter mode (and probes) to DC A mode and again go across the removed fuse terminals (or opened wire) to measure the actual leakage current.
Now recall that even when off, things like stereo, clocks, and such still have a slight current draw which is normal. You may have to disconnect these things when troubleshooting to get them "out of the circuit". In the case of the dome light circuit, there are many paths to ground. On the drawing you will see, for example, 4 door switches in parallel so that if any one (or more) of them are closed, the light comes on. You have to use your head and the drawing to see what all is a possible path to ground. In the Toyota, the ground wires are routed to various points on the body and frame where they are screwed in. You may have to locate these and temporarily unscrew them one at a time to figure out where the problem is, which is usually a bad or incorrect connection. The FSMs have this info, and the schematics are drawn so that 12V is at the top and flow down to grounds at the bottom.
In every used vehicle I have ever owned, I find electrical things that were added, repaired, or modified in a crappy manner, with no heat shrink, twisted together with black or duct tape, and often connected WRONG. I always suspect this stuff first. For example, when I re-did my FJ60's trailer connector wiring recently, I found a horrendous rat's nest of bad connections that was done by retarded spider monkeys. I ripped it all out, repaired the stock wiring, and then installed a new wiring kit properly. Same with stereos and aux panels added by a PO - look upon that stuff with a jaundiced eye.
Hope this helps. If you were in the neighborhood I would come over and help, but all I can do is be a sage and a cheerleader on the internet. Keep at it in a methodical manner until you find the problem. Disconnect non-stock stuff. If you are SURE everything is correct and you still have a problem, then something you are SURE is correct is, in fact, incorrect. Good luck.