Im gettin a code 54 which according to our faq means
Low voltage at fuel pump OR
Low voltage at Fuel pump relay OR
Output failure at quad driver module
im guessin im gonna have to break out the multimeter... but where exactly should i look?... the plug goin into gas tank ? any others?

never had this problem b4 .. jus wanna kno wat i might be lookin at parts wise and $$ wise

thanks guys

 

Not having looked at the exact wiring I'd venture to guess that this is at the output of the fuel pump relay. Which probably means that the relay is starting to go bad.

If anything that is where I would start.

RBob.

P.S. The bank of three relays on the drivers side firewall. One of which is for the fuel pump. Others are A/C and?? (can't remember).

 

You should've started with a <a href="search.php?s="><img src="images/top_search.gif" alt="Search" border="0"></a> on the V6 forum for "code 54"! Here's what you would've found! Good luck, let us know how it goes! And by the way, this chart came from the http://www.helminc.com shop manual- as I said before, everyone here with mods should've bought one already! Throw it on the christmas list!! Here's the chart:
.................................................................................................

-----------------------------------------------
DIAGNOSTIC CHART FOR CODE 54 (2.8L MPFI ENGINE)
---------------------------typed by Tom P------

Preliminary stuff:

Ignition off for ten seconds.
Ignition ON, listen for in-tank fuel pump
Fuel pump should run for 2 seconds after ignition on

Not ok? See "1"
Okay? See "6"



1. Ignition off. Remove the fuel pump relay, but keep the harness connected. This is
____located on the top of firewall, driver's side, on a relay bracket. It's the leftmost
____relay, with a connector that has these wires: Tan/white, black/white, green/white,
____orange, orange.

____With the relay still connected, back-probe terminal "A" (that's tan/white, circuit
____CKT #120) with a test light to ground, make sure you can see the test light from the
____driver's seat. Turn the Ignition to on (don't crank the engine/start the car). The
____light should turn on within 2 seconds.

____Light on? See "1A".
____Light off? See "2".

___1A: Repeat the test on CKT 120 (tan/white) at the rear body connector. You saw this
________connector if you replaced the fuel pump, it's in front of the tank, against the
________top of the underside of the car.

________Light on? Faulty pump ground or pump (ouch!)
________Light off? Fix the open (break) in circuit 120.



2. Disconnect the pump relay. Put the ignition on, engine stopped. Probe the fuel pump
____harness connector, terminal "E" (orange on the edge of the connector, Circuit 340)
____with a test light to ground.

____Light off? See "2A"
____Light on? See "3".

___2A: Repair open in CKT 340, this comes off of both your "computer-and-oil-pressure-
________safety-switch" setup and your "fuel-pump-and-computer-fuse".

________Your fuel pump/ECM fuse is under your hood, screwed down to the upper-frame-rail
________on the passenger side of the car, close to the air cleaner & black fuel-vapor-can.
________You'll see two little black boxes, each with two wires coming out of them, screwed
________down to the upper frame rail by one screw each. One of them has a red wire and an
________ORANGE wire coming out of it- that's your pump/ECM fuse holder. Pop the top off
________to see the fuse. (The holder with red & brown wires is for your 85-89 MAF sensor.)

________Now, two things could happen here. You could have a bad fuel pump fuse- check the
________fuse. If it looks okay, replace it anyway... sometimes a fuse can look good, but
________really be blown. The second possibility- I want you to probe the red wire on the
________fuse holder with a test light to ground. The red wire goes to the positive-
________junction-block on the radiator support- your pump/ECM fuse might not be getting
________any power! If the light doesn't light, check the red wire hookup. However, with
________either case your computer would be acting up, too, and I don't think you could get
________the car to start at all.



3. Connect a test light beteween pump connector pin "B" (black/white wire, CKT450) and
____pin "E" (orange wire from step 2, CKT340).

____Light off? See "3A"
____Light on? See "4"

___3A: Repair open CKT 340. The black/white wire isn't making a good ground. Sorry, I
________don't know where this grounds out to. I'd imagine it goes to a screw on the car.



4. Connect test light between pump connector terminal "C" (dk green/white wire, CKT 465)
____and ground. Ignition to "off" for 10 seconds. Note test light within 2 seconds after
____ignition "on".

____Light on? See "4A"
____Light off? See "5"

___4A: Faulty Relay! Hey that's cool, a $10-$15 part from the GM dealer! But, if you
________replaced that already, something's funny. You might want to do the chart again.
________Check for intermittant connections, possibly caused by dirty connector contacts.
________Note: The manual continues to test the "oil pressure safety switch", I'll put
________that test at the end of this message.



5. Ignition "off". Disconnect ECM A-B connector and check for an open, or a short to
____ground, in circuit 465- that's the dark green/white wire from the relay. It's on
____terminal "A1" of the ECM A-B connector.

____CKT 465 okay? See "5A"
____CKT 465 Bad? See "5B"

___5A: Check resistance across pump relay pins "opposite harness connector terminals B
________and C". Should measure 20 ohms or more to be good.
___________Resistance good? Faulty ECM A-1 connector, or bad ECM
___________Resistance bad? Replace Relay AND ECM.


___5B: Fix CKT 465. If CKT 465 was shorted to ground, re-check for a light "on"
________between harness connector terminal "C" and ground within 2 seconds after ignition
________"on".
___________Get a light? Cool, reconnect your relay
___________No light? Faulty ECM terminal "A1", or bad ECM.



6. Clear codes. Start engine and note service engine soon light. If the light comes
____on, check the code, if it's not 54 or you don't get a light, it's something else
____wrong, or an "intermittant" problem.



7. Backprobe ECM terminal "B2" (that's tan/white, CKT 120) with a test light to ground.
____Ignition off for 10 seconds. Note light within 2 seconds after ignition on.

____Light on? See 7A
____Light off? See 7B

___7A: Faulty ECM terminal "B2" or bad ECM.
___7B: Repair open circuit 120 to ECM terminal "B2".



*** Oil pressure switch test: Our 2.8's have two oil pressure switches. One is for the
gauge panel to control our oil pressure light (or gauge). The other one will keep the fuel
pump running if the relay happens to die while you're driving. I assume the theory was that
if you pull out onto a highway and the relay dies, you don't get killed? Contrary to popular
belief, this switch does NOT turn the pump off if oil pressure goes to zero. That's false,
and can easily be seen by looking at the f-body's wiring diagrams. Anyway...

OP1. Start the engine, get it up to normal operating temperature. If you can, verify that
______the oil pressure is normal. Disconnect fuel pump relay- the motor should keep running.

______Engine stops? Bad oil pressure switch.
______Engine keeps going? See "OP2"

OP2. Reconnect fuel pump relay. Ignition "off". Find the fuel pump test terminal on the
______ALDL (Assembly Line Diagnostic Link, the connector above the driver's feet you used
______to get the error code out), which is terminal "G" -- the bottom leftmost terminal.
______Probe that terminal "G" with a test light to ground.

______Light off? No trouble found! (Doubtful, if you got this far & nothing's wrong...)
______Light on? Bad oil pressure switch. Oh yeah this switch is screwed into your engine
_________________block, right above your oil filter, with an orange and a tan/white wiring
_________________harness on it.



Whew.

-Tom P (Hot rodded 1986 Firebird 2.8l)

 

Well my usually prompt starting 91 rs v6 wouldn't start today. Tries to start but stumbles and stalls. Pulled code 54 from ecu and read all the threads here but most of them mention being able to get the car to run with different methods and then troubleshooting. I hear the fuel pump run for the two seconds when I first turn the key and as I say it's getting something because it tries to start. Could I still be looking at a fuel pump relay situation, or can I assume since the pump is working the relays ok?

 

First off, all you need to do to check ALL of the wiring AND the relay is hook +12VDC between a couple of terms in the ALDL, I can't remember which ones off the top of my head ATM, however (I think it's the top right and lower left ones, looking at it from the front, correct me if I'm wrong). If your car passes this test by running the pump, the ECM is bad.
Second, tycomps, I would look into your oil pressure switch and/or fuel relay or even the ECM being bad. Your pump DOES run for those 2 sec when you hit the key, so the ECM IS sending a signal to the relay. Your oil pressure switch is designed to kill the pump in the event of no oil pressure (collision, no oil, etc) for safety reasons.

:edit: BTW, not all 2.8's have the separate oil pressure units. Some have a 3-wire assembly that does the job of both...

 

This is not correct. The purpose of the oil pressure switch is to bypass the relay and RUN the pump in the case of a relay or ECM driver failure.

RBob.

 

^ RBob is absolutely correct, as I too initially thought the same exact thing about the Oil Pressure Switch turning off the pump, when it doesn't....

By the way, way to bring back an older thread. I thought TomP was back to posting with us for a minute, until I realized it was from '02 lol....

 

You know, it's funny how my fuel pump won't run with the relay connected and the oil pressure switch not...

 

I had the same problem a while ago, code 54. I ressetted the ECM and the code never came back. The fuel pump was fine.

 

Then there is a wiring issue, the relay is bad, or the ECM is bad. Because in your case the oil pressure switch is running the fuel pump. With the engine running pull the relay and see if it stays running.

RBob.

 

Circuit tests fine, so it's not the wiring. Can't be the relay or ECM if the same happens between 2 or more units (of each)... But, it's not worth worrying about, since the car does run fine (except for the lean condition in 2 cyls)

 

Thanks for the great touble shoot step by step TomP! I've got power to the fuel pump buy no pumping, so it looks like bad pump.

Could the pump be confirmed dead by direct wiring voltage from a battery to the tan/white and black on the wiring harness from the pump? I guess there's really no point other than the pump should run this way, yes?

Ps I'm getting my '86 2.8 on the road, bought it March 4th 1986, 28,118 miles. Got a lot of tuning up to do.

Great website!

 

Pull the connector off of the 2-wire oil pressure unit and jump the 2 terminals. One is a battery feed and the other runs straight to the fuel pump... The oil pressure switch is mounted with the idiot light switch or gauge sender by the oil filter (and the sender/switch has a single white wire, so you can't confuse the 2).