Fuel pump relay potential issues (Page 2/3) A_Lonely_Potato JUN 28, 04:59 PM quote Originally posted by theogre: ECM Dk Grn/Wht plug A runs the pump w/ 12v to relay coil when: Turn Key On but not start will run ~ 2 sec. Turn Key Off and wait a few sec then will repeat forever. (Side note: If you work on fuel pump plumbing that allows you to purge air out before you try to start.) Turn Key On then Start will stay On. Turn Key On but not start will run ~ 2 sec but leave Key On for whatever time then start then ECM will turn pump On again and stay on when running. Key On does not trigger the fuel pump as it used to. The pump does run once oil pressure has been built. Can I unplug oil pressure unit temporarily, and attempt to run the car without it, to see if the FP relay circuit will run the pump? quote Basically IF that wire has power w/o engine running then Something is wrong w/ ECM or the wire. Seeing 12v is ½ of issue... If ECM has "blown" driver part(s) for the Relay... may read 12v but no amps to actually turn the coil On. Most if not all ECM "Switches" shown above are MOSFET that die outright, iffy support parts or "just" crack solder joint that are "dead" or doesn't handle power to whatever. Dead MOSFET can fail short or open but short may not be a "dead short" w/ 0Ω The ECM DK GRN/WHT has 0v with key off, 12v with key on. quote Unplug ECM. Check wire for volts, should be 0 now. Now find other end of Dk Grn/Wht. What pin depends on year and engine. and check Ω of the wire. should be near 0. (Likely have help and/or make 1 long probe and read meter thru glass.) Wire has 0.2Ω from the ECM pin to the FP relay pin. quote Blk or Blk/Wht (Depending on year/engine) on plug C is Ground for Relay Coil. It is a good ground, 0.3Ω to engine block ground. quote When have good Relay then Tan/Wht plug B when work same way as Plug A (If Ignore OP Switch...) Not entirely sure what you mean here, sorry. quote Originally posted by olejoedad: The tan/white (12vdc to pump) should energize when the relay clicks. Bad relay - contacts burnt up. Neither relay that was in the car(FP and A/C) will click when plugged in but will trigger when i apply 12v directly. So the relay should be good. I got a new one last night, and its the same story. theogre JUN 28, 08:39 PM OP Switch is a backup for iffy relay or ECM failing to turn on the relay. In your case, Pull the OP sender plug then car will never start. "When have good Relay then Tan/Wht plug B when work same way as Plug A (If Ignore OP Switch...)" Means when have a good relay the power to F-pump follows output from ECM. Last post quote The ECM DK GRN/WHT has 0v with key off, 12v with key on. When ECM is unplugged then a "soft" short w/ resistance in that wire to 12v from anywhere and no amps to turn on the relay. or When connected to ECM Suspect ECM is "Dead" as for power out to the FP relay while ECM seem to work otherwise. Cooked wiring often does either or both. Note: ECM often doesn't set "codes" for problems that can't even start the car. If does set "codes" trying to start is often bogus and mean nothing unless a Scan Tool maybe shows a "dead" sensor. Most times codes set while driving and are old and often there for months to years and mean nothing in your case. A_Lonely_Potato JUN 29, 09:22 PM The fuse for amperage is blown on my multimeter. Gonna get a new fuse to check current coming from the ECM to the relay. Spent today trying to get my clutch working. bled the system yesterday and now my clutch is gone, woo theogre JUN 29, 09:56 PM Testing amps w/ shut in Fluke 77 or any other from ECM likely won't help and may give bad data or worse. I never use a shut meter now because have to "splice" the probes and often just make more problems. If you're trying to see amps is better to have DC Amp Clamp (Most also read AC Amps.) Example: https://www.amazon.com/Uni-...itance/dp/B00O1Q2HOQ Can use that for everything in a car except starter circuit drawing 120+ amps. I have a couple bigger units that read 200+ amps so I don't have this but very popular on YT and not just maker gave them to everyone. A_Lonely_Potato JUN 30, 05:47 PM quote Originally posted by theogre: Testing amps w/ shut in Fluke 77 or any other from ECM likely won't help and may give bad data or worse. I never use a shut meter now because have to "splice" the probes and often just make more problems. If you're trying to see amps is better to have DC Amp Clamp (Most also read AC Amps.) Example: https://www.amazon.com/Uni-...itance/dp/B00O1Q2HOQ Can use that for everything in a car except starter circuit drawing 120+ amps. I have a couple bigger units that read 200+ amps so I don't have this but very popular on YT and not just maker gave them to everyone. Why would I need to splice anything? Could I not read the current from the prong on the relay harness? And why would that give bad data? I know this is a lot of questions, i'm just trying to understand. It seems the most likely point of issue is my ECM right now, is that what you believe it may be? A_Lonely_Potato JUL 02, 04:37 PM I think ive isolated the issue to my ECM. Ran seperate wires from the ECM pin to the relay, and a new ground wire. Same issue. Found a thread as old as i am stating the exact same issues im having, and when they replaced their ECM it solved their case. Is an ECM from rockauto reputable or is there someone here on the forum? theogre JUL 03, 01:30 AM No. don't get important/critical parts from RA Ebay etc. More so if parts have a Core Charge. get at AZ and real parts stores. AZ, Advance Auto and some others can order online, often w/ better discounts and free shipping, then return core etc to local stores so you don't pay return shipping or have problem like X saying didn't get a core or other BS and not paying. Plus AZ and some others have better warranty too. Make sure you careful pull the PROM/MEMCAL in old ECM. You need that for new ECM. phonedawgz JUL 03, 04:19 PM I can't imagine that any ECM you get is just a refurbished ECM. I would just pick up a cheap used ECM and run with it. Have the output driver transistor for the FPR output replaced and then keep your original as a spare. A_Lonely_Potato JUL 07, 03:17 PM Got an ECM from autozone, with a 1 year warranty to boot. swapped over my PROM and the other chip(MEMCAL?) and bingo bango the pump primes, and everything is back to usual. Thanks for the help guys, especially ogre steve308 JUL 07, 09:49 PM Now that it's running wrap the wires with a new heat resistant material! I had the wire loom that runs from the relay catch fire! and it resulted in a compromised wire just like you did. Remember that the factiory protective wrap is 30+ years old. I got this from Amazon.....cheap insurance A-Team Performance - Heat Shroud Aluminized Sleeving for Ultimate Heat Shield Protection Barrier with Hook and Loop Closure - 1" x 36" (3ft), 500 degrees F direct and 2000 degrees F radiant heat