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Appreciate it, thank you for the diagram. It's as I suspected. There's nothing between the fuel pump relay (55), like another fuse or relay, which could break the connection.
I've bypassed the fuel pump relay and attempted to send 12V to the pump from relay socket (G7).
I've taken apart the fuse box and attempted to send 12V to the pump from the appropriate connector below.
Tomorrow I will take out the wheel liner and get to the fuel pump connector and try from there.
Yes, I have several DMMs. I'm a EE.
I replaced this pump 2 years ago due to the fumes problem. Might have a bad one that has given up too quickly.
If you aren’t familiar with automotive electrical diagrams you have 3 connectors (X184,X420 and X459)…between the relay and the pump and the 2 “decision” boxes above X184 represent RPO codes (located in the glovebox) and since you have an MT which is RPO MM6 and you can also see F55 (with mag ride) and -F55 (without magnetic ride control) so that determines what terminal number at X184 you would use…if you are familiar with voltage drop testing and have some back probes or piercing probes you can do that at each of those 3 terminals but I’m sure you know current must be flowing to do that…”no current flow no voltage drop”…as a substitute load I use a headlight bulb that draws 5 amps and connect at X459…I will provide the connector view of X459 in the next post.
Located outboard of the battery and is the biggest of the 3 connectors there…on your 2010 it looks like an oval shaped connector IF you have F55. Is on the right rear frame rail below the EVAP vent valve Forward section of the left rear wheelhouse liner
No problem !!…did you give it a good ground also ???…you NEED to check the ground circuit also..I use a high beam bulb to check grounds pictured below…if I connected to B+ and probe a ground if the headlight is bright the ground is good…if mega ohms range the pump is toast… pump draws around 8 to 9 amps so one would expect roughly 1.5 ohms using Ohms Law…you may be able to go into the fuel filler pipe and suction out the fuel…there is a check valve at the bottom of the filler pipe but that keeps the fuel from coming back out…BTW I’d substitute the fuel pump with that high beam bulb and then voltage drop both ends of the circuit…static OCV testing which you did doesn’t tell me anything !!
I would put 12 volts from your power supply on terminal A at X459 and run a length of wire from battery negative and run it to terminal D…the fuel pump ground is G401 which is on the left rear frame rail..you can see it there…to do this testing I use my Power Probe 4 which connects directly to the battery…I can supply 12 volts with a rocker switch and can attach my ground to the negative connection on the Power Probe.
You’re the EE so do whatever method you find acceptable…LOL !!…I just like to dynamically load test these circuits but that’s just me and what I’ve been taught by some of the best automotive instructors in the country over the years…good luck if it’s a bad pump.
You’re the EE so do whatever method you find acceptable…LOL !!…I just like to dynamically load test these circuits but that’s just me and what I’ve been taught by some of the best automotive instructors in the country over the years…good luck if it’s a bad pump.
And yes, that makes perfect sense for intermittent load dependent discontinuities, like burnt connectors, heat warped spring connectors for relays, anything that's arcing, etc.
But if I put 12V right across the motor and it does not come on, and it reads in the megaohms, it's more than likely OPEN. Won't matter if I run lines from the battery or not.
How do I best get the fuel out of the tanks is my next thing. Wonder how much I can get out (if any) by connecting a pump to the fuel line under the hood and sucking it out that way.
Yes, you’re reading Meg ohms the pump has failed so no need to check anything else…gas weighs about 6 pounds per gallon so even if the left tank were full that’s only about 50 pounds…might be a good idea if you replace the pump clean all those connectors with DeOxit and use some of this stuff if you’ve ever heard of it…Stabilant 22…about $60.00 for a dropper size bottle.
Dropping that tank at say 60# (50# fuel, 10# tank) is not doable. Not sure if you've ever done that job before but there's a lot of fenneglaing you have to do with the xover tube, emissions tubes, fuel filler tube, etc., etc, which would be a nightmare if the tank is coming in at 60# and potentially sloshing fuel from the top and the fuel line loop.
Last time I did this, the fuel pump was working, so emptying the tank was a breeze.
I can't believe I'm back at this 2 years later but with all these cheap *** mexican and chinese made parts, I can believe it.
I don’t know if you are using a lift or a quick jack but you may be able to find a cheap foot operated transmission jack on Amazon that can hold the tank as you drop it.
I don’t know if you are using a lift or a quick jack but you may be able to find a cheap foot operated transmission jack on Amazon that can hold the tank as you drop it.
Roger that. I have QJs.
Last time I made some wooden support that sat on a regular floor jack (pretty janky) and put that under there to help me lower it while I disconected everything. That's why the thought of doing that at 60# is a no-go. At least for me.
Gotta figure out how to drain it.
Last edited by AtlantaRob; Jun 15, 2025 at 07:28 PM.
I'm wondering is you also have the schematic for the fuel level senders. Everything has been fine since that repair back then but yesterday out of the blue my fuel gauge just dropped to zero. So I wanted to take a look at the schematic and see how that might happen. Maybe it's not the senders in the tank, but something wiring related.
I'm wondering is you also have the schematic for the fuel level senders. Everything has been fine since that repair back then but yesterday out of the blue my fuel gauge just dropped to zero. So I wanted to take a look at the schematic and see how that might happen. Maybe it's not the senders in the tank, but something wiring related.
Thanks!
Rob
No I don't. !!...you can get a 1 month subscription to Alldata DIY for $19.99...has all OEM wiring schematics !!
2010 MT Fuel Pump Circuit Schematic
