so the brain box is flashing code 42, the fuel pump, thing is a coulpe weeks ao it left me stranded, the pump would prime but not energize with the car running causing a stall, (the car does have a fuel pump rewire kit, and a wally 255 the loud one) so I ran a wire from the fuse tray to the pump rewire relay so its energizing the pump anythime the ignition is on, have been running it like this for some time know, but I would like to clear the light code, so do I need to change the fuel pump relay, if so were is it at? anyone?
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CEL code 42?
- Thread starterdsmless
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after ding some reseaching, the pump will prime as the ignition is on but then at start up hte ecu is not seeing that the fuel pump is running. That throws the CEL
check this I copied from the TMO website,
Quote:
Originally Posted by Quasimondo
I've been looking over the diagrams. It appears that the MPI for the fuel pump has two coils. One is powered by the starter relay, the other is powered by the igniton switch and ecu. We can pretty much ignore the coil from the starter relay, that only engergizes when you're starting the car (which would explain why the engine has no problem starting)
Correct. The MPI relay has two functions. MPI power and Fuel Pump power.
The Fuel pump power relay has two coils, one activated by the starter circuit getting 12v and the other activiate by the ECU pulling the pin to ground. The feeds for these come from either the MPI fuse or the ignition fuse on the battery.
Quote:
Originally Posted by Quasimondo
The other coil gets its power from the ignition switch and the the ecu (pin B56). When that pin grounds out, it energizes the coil (that's how it looks to me). I would assume that pin isn't grounding out, but that doesn't explain how your car can still run. I doubt it's a break anywhere in the ignition switch wiring because your fuel pump wouldn't work. The same wire that powers the coil on the relay also provides power to the fuel pump.
Close. One of the two coils is powered by the starter circuit and it's other end is grounded where the otehr coil has the hot side tied to the same power source as the FP side is switching and it's other end goes to the ECU. So the starter circuit coil is activated by getting 12v and the ECU circuit coil by grounding it.
Quote:
Originally Posted by Quasimondo
The the last part of the wiring is a wire that is between the relay and fuel pump. That wire runs back into the ecu (13C) and it looks like a signal wire to let the ecu know that the fuel pump is running. If that wire doesn't get any voltage, it throws a CEL.
Correct. Pin 13 isn't shown in most FSM but it's the sense line to the ECU that the fuel pump is getting power and throws a 42 code if the pump is activated by the ECU and 12v isn't seen on pin 13.
Quote:
Originally Posted by Quasimondo
This makes me believe it's software related. If it was anything with the wiring on either the ignition wiring side or the ecu side, then the car wouldn't run.
The traces for running the fuel pump on the ECU run through the danger zone on the ECU for capacitor leakage damage. I fix a few a month where the cap leaked and the electrolyte eat the trace up disconnecting the edge connector from the logic.
>>
check this I copied from the TMO website,
Quote:
Originally Posted by Quasimondo
I've been looking over the diagrams. It appears that the MPI for the fuel pump has two coils. One is powered by the starter relay, the other is powered by the igniton switch and ecu. We can pretty much ignore the coil from the starter relay, that only engergizes when you're starting the car (which would explain why the engine has no problem starting)
Correct. The MPI relay has two functions. MPI power and Fuel Pump power.
The Fuel pump power relay has two coils, one activated by the starter circuit getting 12v and the other activiate by the ECU pulling the pin to ground. The feeds for these come from either the MPI fuse or the ignition fuse on the battery.
Quote:
Originally Posted by Quasimondo
The other coil gets its power from the ignition switch and the the ecu (pin B56). When that pin grounds out, it energizes the coil (that's how it looks to me). I would assume that pin isn't grounding out, but that doesn't explain how your car can still run. I doubt it's a break anywhere in the ignition switch wiring because your fuel pump wouldn't work. The same wire that powers the coil on the relay also provides power to the fuel pump.
Close. One of the two coils is powered by the starter circuit and it's other end is grounded where the otehr coil has the hot side tied to the same power source as the FP side is switching and it's other end goes to the ECU. So the starter circuit coil is activated by getting 12v and the ECU circuit coil by grounding it.
Quote:
Originally Posted by Quasimondo
The the last part of the wiring is a wire that is between the relay and fuel pump. That wire runs back into the ecu (13C) and it looks like a signal wire to let the ecu know that the fuel pump is running. If that wire doesn't get any voltage, it throws a CEL.
Correct. Pin 13 isn't shown in most FSM but it's the sense line to the ECU that the fuel pump is getting power and throws a 42 code if the pump is activated by the ECU and 12v isn't seen on pin 13.
Quote:
Originally Posted by Quasimondo
This makes me believe it's software related. If it was anything with the wiring on either the ignition wiring side or the ecu side, then the car wouldn't run.
The traces for running the fuel pump on the ECU run through the danger zone on the ECU for capacitor leakage damage. I fix a few a month where the cap leaked and the electrolyte eat the trace up disconnecting the edge connector from the logic.
>>
Yes, the reason it is throwing the code is because you are bypassing the fuelpump relay. Its probably acid damage, as that post discusses, which keeps the ECU from pulling in the MFI relay. Have the caps been replaced? You either need to get the acid damage fixed, or connect pin #13 to your fuelpump bypass, so that it sees 12 volts whenever the fuelpump is running, to stock the CEL.
Yes the ecu has had the caps replaced and is socketed, the previous owner had it done proir to me buying the car, it has run flawlessly for 2 years and never had the CEL coome on, I was thinking about runing a hot wire to pin 13 good thing you also mentioned this, also my car went into safe mode I beleive because its running hella rich and is chugging 91 octane like a waterbuffalo in an oasis, can anyone confirm this?
stevep
Well-known member
Pretty much all I can tell from the pictures is that Posten worked on it but it doesn't look like he did anything more than change the caps. Since the fuel pump control didn't work there may be other things in there cooking too.
I don't usually just see one trace opened when I fix those sorts of problems.
I don't usually just see one trace opened when I fix those sorts of problems.
Jason G.
Well-known member
I'm way late, but I'm the PO of the car and I had Terry do the caps and socket the ECU back in '06 I beleive.
Any update on the issue Sam?
Any update on the issue Sam?
Hey Jason hope alls well the issue is the same I have been driving it like that until I get a good deal on a dsmlink with ecu or a aem stand alone will see what comes first other than that I am trying to sort out my radiAtor issue at the moment
I have the same CEL code. I have checked the 13th pin and there is 12V on it.
I know from dsmtuners that on DSM ecu it is possible to short TR17 transistor to remove this CEl.
There is no TR17 on GVR4 ECU.
Does GVR4 ECU have the transistor with the same functions?
I know from dsmtuners that on DSM ecu it is possible to short TR17 transistor to remove this CEl.
There is no TR17 on GVR4 ECU.
Does GVR4 ECU have the transistor with the same functions?
transparentdsm
Well-known member
^ it may cost to ship overseas, but send it to ecmlink. they have 10 or 15 dollar work blocks and there turn around time is crazy fast. unless your a circuit board wiz with all the parts and knowhow its not worth screwing around. every time i get a new ecu or dsm/vr4 i send them the ecu now to have it clean and checked and repaired if needed. its more then worth it for the 18 or so dollars to send it out and have it checked it to know my ecu wont be a problem.
