Q: Please help me diagnose an electrical drive by wiring

asked by on

I performed pin by pin test on wiring according to manufacturers service manual, I have two seemingly ambiguous results, the first is 50.7 ohms of resistance in the F terminal of the APP wiring terminal and the main relay terminal A. I attributed this to the evap leak detection pump which shares this wire since that is at the top end of normal resistance between power and ground (terminals A & B) for that component. Is this correct? Secondly in the manufacturers (mazda) manual it refers to continuity between the ground terminal and the power supply of both the APP and the Evap leak detection pump as a short circuit. Isn't that a complete circuit and totally normal?
My car has an automatic transmission.

Hello. Generally speaking, most automotive circuits have very low resistance, usually less than 50 ohms. Unless there is a resistor, or sensor that acts as a resistor between the APP wiring terminal and main relay terminal A, then there may be some sort of wiring issue causing the excessive resistance. I would refer to a service manual or dealership for specifics on what the readings should be for the circuits in question. If the manual indicates that there should be no continuity between those circuits, then that may indicate that those circuits have grounds that are switched on an off, usually by the computer. If you are getting readings outside of normal range then it may be possible that there is an issue with your test leads, or a wiring issue with the circuits in question. Contact a professional mechanic, such as one from YourMechanic, if you want to have a technician inspect your circuits for you.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Please help me diagnose an electrical drive by wiring

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: AT light on

One of the most common causes for this light to come on is the transmission input speed sensor goes bad and the transmission module connector. If you have the system scanned you would get codes pertaining to the input speed...

Q: Leaking power steering oil

You do have a leaking power steering system and if you cannot locate the leak then it may be collecting in the inner tie rod boot and leaking from the rack and pinion side seal. If you're unable to pinpoint...

Q: Just replaced set of front bearings on 2007 cadillac escalade ext. Charged $360 each isn't that high for the parts. This was done

The AC Delco hub bearing assembly for your vehicle costs about $180, per side, on Amazon. Off brand versions of this part are NOT recommended but are obviously even cheaper. The labor time to remove and replace BOTH sides is...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...