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Hi there folks. I just purchased a 2007 GL 450 knowing that it was a 'crank no start' (I got a great deal). After getting it home I dove in. First thing first I checked fuses and to my surprise the fuel pump fuse in engine bay was blown. I replaced the fuse and hoped for the best but nothing. No fuel pressure at the rail. I bit the bullet and replaced the fuel pump with still no success. I found the fuel pump is not turning on. I can jump the fuel pump relay in the rear load area and turn the fuel pump on and vehicle starts and runs great. I have combed through wiring diagrams on 'Alldata' and have tracked all wires related to the fuel pump and seem to have continuity on all the wires (point to point). The only code that it is throwing is a p2088 which has nothing to do with fuel and as I said the truck seemed to run fine when relay was jumped. I have pulled the rear sam unit and there are no signs of water/corrosion. Am I wrong on thinking that the next issue may be the ECU? Any help/guidance would be greatly appreciated.
Hi there folks. I just purchased a 2007 GL 450 knowing that it was a 'crank no start' (I got a great deal). After getting it home I dove in. First thing first I checked fuses and to my surprise the fuel pump fuse in engine bay was blown. I replaced the fuse and hoped for the best but nothing. No fuel pressure at the rail. I bit the bullet and replaced the fuel pump with still no success. I found the fuel pump is not turning on. I can jump the fuel pump relay in the rear load area and turn the fuel pump on and vehicle starts and runs great. I have combed through wiring diagrams on 'Alldata' and have tracked all wires related to the fuel pump and seem to have continuity on all the wires (point to point). The only code that it is throwing is a p2088 which has nothing to do with fuel and as I said the truck seemed to run fine when relay was jumped. I have pulled the rear sam unit and there are no signs of water/corrosion. Am I wrong on thinking that the next issue may be the ECU? Any help/guidance would be greatly appreciated.
I don’t have a lot of time right now but if you search the forum you should find some diagrams.. when I was troubling shooting there was wiring diagrams put online. Do you have a fuel pump regulator ? Make sure you search for it.. I did not have one but I believe most GL’s have a regulator..
vesiadog thank you for your reply. I don't believe my vehicle is equipped with the 'fuel pump module'. I saw that same image in Alldata and in some of the wiring diagrams but I'm assuming some came with it and some use just the basic relay circuit to power the pump? From my understanding the fuel pump relay socket has a 'always hot 12v, the switched pole to the fuel pump harness, one slot goes to the ECU (ME) and the other goes to fuse 105 in engine bay. I have tested all circuits for continuity and they all test good. Not sure what's going on. I'm wondering if there is some other issue that would interfere with the fuel pump circuit? I am also wondering if the fact that it had a blown 105 fuse (fuel pump) could give some kind of clue. After replacing the fuse/fuel pump and jumping the relay the fuse still has not blown.
vesiadog thank you for your reply. I don't believe my vehicle is equipped with the 'fuel pump module'. I saw that same image in Alldata and in some of the wiring diagrams but I'm assuming some came with it and some use just the basic relay circuit to power the pump? From my understanding the fuel pump relay socket has a 'always hot 12v, the switched pole to the fuel pump harness, one slot goes to the ECU (ME) and the other goes to fuse 105 in engine bay. I have tested all circuits for continuity and they all test good. Not sure what's going on. I'm wondering if there is some other issue that would interfere with the fuel pump circuit? I am also wondering if the fact that it had a blown 105 fuse (fuel pump) could give some kind of clue. After replacing the fuse/fuel pump and jumping the relay the fuse still has not blown.
I would look at the turn on signal for the relay.. sounds like you are not getting it or there is a problem with the wiring or ECM.
I would also be concerned about what blew the fuse???
That last photo doesn't really look like the fuse/relay area like in my vehicle unless maybe it's a different version or something. I have noticed on Alldata it shows some modules and photos that are not the same as my model. Anyhow I do believe you may be right. I assume the relay gets its signal from the ECU to turn on. I tested continuity from the relay socket to the respective plug on the female side of the ECU connector and do have continuity. I can feel/hear the relay click when the ignition is turned but something is still off somewhere. Unless as I've stated maybe the actual ECU itself isn't sending the signal or something. I even opened the ECU to see if I could see any obvious corrosion/burnt components but nothing. Thanks again for your feedback!
This is what the rear fuse area looks like on mine. Out of curiosity can you explain the pull handle with fuel tank on it? I'm assuming it's a manual release for the gas tank lid? I pull it but it does nothing
I have been messing about a little bit more and I measured voltage from the relay socket and the space where the signal comes from the ECU is only showing around 4v? Is this right? Or should it be around 12?
On the 07 you have everything integrated in the pump unit itself. Search my thread for how I did it on mine, but I would recommend you check for 12 V at the pump connector underneath the passenger rear seat.
Yes I have attempted this and I am not getting any voltage anywhere. All wires have continuity. It works when relay is jumped so I assume the wires have some connection but there has to be an issue somewhere with it not getting signal to cut on . Can you kindly direct me to the post you are referring to? I see you have quite a few posts so it may make it difficult to find. Thanks
Just to note: the fuel gauge works fine as well and I assume this circuit is tied into that connector as well?
When I first got the car started by jumping the fuel pump relay I heard the compressor(s)? kicking on and the vehicle raised a bit. The previous owners said that they had just had the whole suspension replaced (compressor I guess and bags?) Since then the vehicle has stayed in that position.
I want to also note upon starting and running the vehicle I have a message that says there is a probably with abs and esp but I don't believe that would have anything to do with the fuel pump correct? I assume that would be a possible issue with wheel sensors ?
I want to also note upon starting and running the vehicle I have a message that says there is a probably with abs and esp but I don't believe that would have anything to do with the fuel pump correct? I assume that would be a possible issue with wheel sensors ?
Now you got me definitely wondering if you don’t have a rear Sam problem. ??
I was able to get it fixed. The fuel pump relay was not making good contact with the pins in the slot connection. I bent the legs of the relay ever so slightly to aid in contact and it fired right up. I will attempt to pull the rear fuse box and see if I can some how address the pins in the socket. I know there are bulletins on this issue but it calls for replaced the whole rear box. A few bent legs later and it works great 👍. Thank you to everyone that chimed in with suggestions.
I was able to get it fixed. The fuel pump relay was not making good contact with the pins in the slot connection. I bent the legs of the relay ever so slightly to aid in contact and it fired right up. I will attempt to pull the rear fuse box and see if I can some how address the pins in the socket. I know there are bulletins on this issue but it calls for replaced the whole rear box. A few bent legs later and it works great 👍. Thank you to everyone that chimed in with suggestions.
Take a look on ebay and buy a nice clean corrosion free box . Buy from a 99-100% seller.
06-28-2024, 01:32 PM
. Can you kindly direct me to the post you are referring to? I see you have quite a few posts so it may make it difficult to find. Thanks
