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Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, Tech Trainer
Category: Toyota
Satisfied Customers: 1516
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Thanks! I have a draw on my battery. I have hooked up my amp

Customer Question

Thanks! I have a draw on my battery. I have hooked up my amp meter and found that when i pull the dome fuse it stops the draw.
JA: Have you checked all the fuses? Do you have a wiring diagram?
Customer: well the draw goes down to zero when the dome fuse is out
JA: What is the model/year of your Toyota?
Customer: its a 1998 tacom tacoma 2.7 l 4cyl extracab
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: yes I am
JA: Anything else you want the mechanic to know before I connect you?
Customer: i have pulled the cd player out and pulled the light bulb for the back seat
Submitted: 2 months ago.
Category: Toyota
Customer: replied 2 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Juan Crespo replied 2 months ago.

Hi there.

Does the dome lamp stay on with all doors closed? Any warnings on instrument panel indicating a door is open?

Customer: replied 2 months ago.
No the dome light does not stay on when in the door is closed when in 'door' mode, it does stay on however when switched to the 'on' mode. No there is no indication on the instrument panel that the door is open, not even when the doors are open. I don't think there ever has been.
Expert:  Juan Crespo replied 2 months ago.

Thank you for that information - usually, we see bad door switches as the main cause, but of course, the dome light does stay on. Since this not the case with your truck, we need to go deeper in the circuit to find the load responsible for the draw; that would be the integration relay in the Junction Box located in the lower left finish panel under the dash (see attached graphic). The circuit is constantly powered and gets ground whenever the lamps are manually turned on or the door switches are closed.

Testing these circuits will require you to use a voltmeter. Would you be able to do that, plus follow the current path on a diagram that I would upload?

Expert:  Juan Crespo replied 2 months ago.

Here is that graphic.

Customer: replied 2 months ago.
i can give that a try. Also, i should have you know that my truck has manual windows.
Expert:  Juan Crespo replied 2 months ago.

As luck would have it, how the windows are powered has no bearing on our issue.

Back to our integration relay (which is actually the whole printed circuit board), get in the truck and, with all doors closed and all interior lamps off and set to open with doors, check that there is no ground at the terminals I've highlighted with a Blue/green square on the attached diagram. If there is no ground, but the draw it's still there, then the Integration Relay needs to be replaced - hang on to your hat; that thing sells new for close to $300! (click here to see example)

Please let me know how you make out.

Customer: replied 2 months ago.
Hey, sorry for the delay. I haven't had time to get back to fixing my truck. I did the test on the integration relay. There was no grounds and I am still getting a draw. After I checked that, I noticed that there is still a 2-3 m amp draw even when the dome fuse is pulled and the draw seems to jump around quite a bit.
Expert:  Juan Crespo replied 2 months ago.

Looks like we're back at what I had posted previously "If there is no ground, but the draw it's still there, then the Integration Relay needs to be replaced". Used units are still available for under $100 - click here to go to sample online vendor's website.

Please let me know if you have any other questions or concerns.

Best Regards.

Customer: replied 2 months ago.
I will be replacing the relay. Any idea why I am still getting a draw with the relay unplugged?
Expert:  Juan Crespo replied 2 months ago.

On your original post, you stated "the draw goes down to zero when the dome fuse is out", so how can you still have a draw when you have not only the dome light fuse out but the whole fuse box/integration relay assembly unplugged?

Customer: replied 2 months ago.
Sorry I typed wrong. The draw is gone when the dome fuse is pulled, but I have 2-3 m amps when the integration relay is pulled.
Expert:  Juan Crespo replied 2 months ago.

I'm sorry if I didn't explain it better - the integration relay is part of the junction box and cannot be disconnected or removed separately from it. In other words, you would have to disconnect the entire junction box to disconnect the integration relay. Since the junction box includes the dome light fuse, disconnecting it would interrupt power to that fuse.

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