Thread: P0230 2005 GP 3800 Please help!!!

A couple weeks ago my wife's car would randomly stall. No codes would be kicked and no SES light. I replaced the Ignition coils, ICM, and finally Crankshaft Position Sensor to fix the issue. At the same time, since she had complained of having little heat over the winter, I replaced the heater core and thermostat. I also changed the transmission filter and fluid, since I was fixing/replacing everything else - it seems. After replacing the CKS, it ran fine for a while. Then the SES light came on and my scanner read a P0420 code. So I checked the cat for rattle, smelled the exhaust, and then replaced the downstream O2 sensor. No change. It still ran fine other than the SES light. Then, driving around town a few days ago the engine surged a few times then it stalled. I started it up again but it promptly died after putting it in gear. I had it towed home. I tested for fuel pressure and there was none. I checked the fuses and relay which tested good. I thought it odd to have fuel pump go out coincidentally so soon after doing so much other maintenance, but I had no other ideas what it could be - and all diagnostic signs pointed toward fuel pump. (I sprayed gas into the intake and it would start/idle until it burnt off.) So I replaced the fuel pump. But it still will not start. The pump will not even kick on. There is no fuel pressure. Does anyone have any other ideas?

Originally Posted by Fivefingerdeathpunch

http://www.gmforum.com/obd-ii-troubl.../p0230-284079/

Swap relays?

I've already done that. :-/ I've tried the A/C and the horn relay in place of the fuel pump relay. Last night, I removed the wiring harness from the trunk area that supplies power/etc to the fuel pump and put my volt meter on that. I'm getting the 5 VDC for the pump. Yet, it is not turning on. Maybe I loosened the connectors trying to put the tank back up. I don't know.

MAF? any broken vac lines?

Sent from my LG G3

Originally Posted by ssuttle1

I've already done that. :-/ I've tried the A/C and the horn relay in place of the fuel pump relay. Last night, I removed the wiring harness from the trunk area that supplies power/etc to the fuel pump and put my volt meter on that. I'm getting the 5 VDC for the pump. Yet, it is not turning on. Maybe I loosened the connectors trying to put the tank back up. I don't know.

5VDC? Shouldn't the pump run at 12 or better?

Jeff

OK. Here's the latest. I found the wire harness that went to the pump harness from inside the car and could not read any voltage more than 5 VDC. But, as J57ltr stated, I found out that the pump needs 12 VDC to run and the two wires with the 5VDC are for the fuel level sensor/float. After beating a 14 gauge copper wire flat I re-tested the voltage I was getting at the fuel pump relay, unplugging the relay of course. I had nearly 15VDC at the relay! So I began thinking again, bad relay. I bypassed the relay by jumping pins 30 and 87 and immediately the fuel pump kicked on! I started the car and it ran fine. I removed the jumper and replaced the fuel pump relay. But noticed that the relay does plug in or sit as tightly as the other fuses and relays in the box. After further inspection, The four receiver pins, IN THE BOX, are too worn to hold the relay properly. Junction boxes are not cheap. And they're not readily available nearby either.

Anybody have experience jerry-rigging a junction box to work again? Or moving a fuel pump switch/bypass to the interior of the car so that one may turn the pump on and off without popping the hood each time? LOL

OK. So I removed the junction box, opened it up and tweeked the blades to make better contact with the relay. After reassembling - it STILL doesn't work. No better. No worse. I can still bypass the relay with a wire jumper to turn the fuel pump on and the car will run fine. But the relay will not operate the pump. I've swapped it out with a few known working relays and a new one too. The relays are fitting much tighter into the socket now also. Any ideas?

Something isn't making contact if you can jumper it and the relay doesn't work. I doubt there is anything as far as fusing on the coil side, but is it possible that you fried the output for the relay when you were jumping contacts?

Jeff

Well, the latest and greatest is - I threw in the towel and took the car to the dealer. The mechanic found an open on one wire leading from the PCM to the junction block. So the relay was not getting the go ahead and run signal from the PCM. Car ran well for a few days and now the SES light is back on (I suspect a P0420 code but have not had a chance to check it yet). And my wife said the other day, as she was driving, the car chimed at her alerting her of "Low Fuel" and the gas gauge had dropped to below "E". She knew she had gas in there but got a few more gallons anyway. When she started the car the needle on the gauge went to full for a few seconds, the Low Fuel warning went away, and then the needle dropped to the correct level.