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Hi guys, I'm looking for a source for either a new (GM discontinued part) or refurbished
Engine Wiring Harness Junction Block (Main Fuse Box)- GM (22739140) as you may know, there's a known issue with the clips in the box that contact the pins for the electric fuel pump relay. They overheat and lose contact overtime. I have re-positioned that clip several times which is just a Band-Aid. It continues to fail so I'm looking for the box itself preferably new or refurbished. Lyle at C&C Corvettes Identifies the issue here:
Not Going to watch the video, but what causes the problem is the internal contacts on the relay itself, get slightly corroded over time to cause the problem down line, and if you replace the relay as the relays upper case started to discolor, or just pop the top of the relay cover off to clean the internal contacts. problem does not happen in the first place.
As for lower fuse block connector, Mouser sells them so easy to replace, and on upper fuse box, easy enough to pull it apart to not only clean the corroded U clip, bend it back to shape, and even temper the U clip so it not bending back open with ease.Hell, push comes to shove, mouser even sells the U clip if you just want to replace it in the upper fuse box.
Hence entire problem can be solved for few pennies in the first place from not replacing or cleaning the relay when it first appeared to start looking burnt, and just a little labor time now.
The other problem that can happen, changing out the fuel pump to after market with more current demand, while the wire gaging is not large enough to carry the load, causing not only problems up at the fuse box, but problem with wire in the loom to the back doing a melt down as well.
Thanks guys very helpful information. The only additional challenge that I had not mentioned is that the U clip that the relay pins plug into in the fuse box overheated so badly that it melted itself into the housing of the box itself, so I can’t even remove it to replace it! I did locate an entire box unfortunately This fix is going cost me about $450.
One more question someone else had mentioned that once the new box is installed it has to be flashed to the ECU which doesn’t make sense to me unless there’s a computer in the box itself that I’m not aware of any insights to that?
OK, I’m back to square one. I just got notified by GM parts store.com that the box that I had ordered is actually not available they issued a refund so I’m back to square one if anybody has a lead on that main fuse box/junction box. 🙏
No on the reflash needed, and guess we are talking upper fuse box, and not one of the lower blocks.
On upper fuse box, ebays has them for sale all the time used,
and if push comes to shove, heat gun to remove the U connector and reinstall a new one, will solve the slightly melted plastic housing problem.
But does come back to why you cooked the first one, and have you solve that problem so your not going to cook another.
No on the reflash needed, and guess we are talking upper fuse box, and not one of the lower blocks.
On upper fuse box, ebays has them for sale all the time used,
and if push comes to shove, heat gun to remove the U connector and reinstall a new one, will solve the slightly melted plastic housing problem.
But does come back to why you cooked the first one, and have you solve that problem so your not going to cook another.
OK Dano thanks again I will pull the assembly apart this weekend and see if I can get that clip out.
Do you have a link / number for Mouser? I l looked through the other thread and didn't see one.
Next it sounds like just replacing that relay will fix the original problem. Is that correct?
Same problem as the OP. I replaced the fuel pump on my 08 last week. Now the relay has intermittent contact in the upper fuse block. I do not want reoccurring issues with no crank due to the fuel pump relay not making good contact with those tiny OEM terminals in the top of the fuse box so the plan is to add an external relay and wire it into the OEM trigger wire. I think the trigger wire for the relay is dark green and white but I am not 100% certain. The ground and 12 volt power for the new relay is simple and the fuel pump's 12 volt power wire is a large grey wire. No need to replace that wire if the issue is only at the relay. The Racetronix wiring harness does not bypass the OEM relay. It only adds a better 12 volt power source for the pump after the OEM relay. If the OEM relay is not making good connection because of heat damaged terminals,, the easiest and most dependable method, in my opinion, is the bypass the OEM relay.
upper fuse box is easy to pull apart to clean the U tabs if burnt and even bent them back inwards if bent too much open. Also, give you a chance to clean the rest, since GM used no kind of lube/perservitive spray on the parts (or any connector), to keep them from corroding up to begin with.
Same goes for the lower block connector as well.
Truth is, the only time you need to go to external relay, is when you replace the fuel pump to something that is drawing more current, and the the oem wires from the fuse box to pump on oem harness, are not large enough to take the extra load without out the doing a melt down in the first place.
OK guys my last fix of going into that block cleaning and repositioning that clip that interface is with the fuel pump relay on top has failed again it's lasted a little almost 2 years!
When I went in there to attempt to replace that clip it had already melted into the block itself and was not able to pull it out even with the heat gun.
Is there any way to replace the entire block? And if so, what's involved I see it's a direct wire to the harness and or any ideas on how to get that clip out and the sources for that clip?
No on the reflash needed, and guess we are talking upper fuse box, and not one of the lower blocks.
On upper fuse box, ebays has them for sale all the time used,
and if push comes to shove, heat gun to remove the U connector and reinstall a new one, will solve the slightly melted plastic housing problem.
But does come back to why you cooked the first one, and have you solve that problem so your not going to cook another.
OK Dano my last fix of going into that block cleaning and repositioning that clip that interface is with the fuel pump relay on top has failed again it's lasted a little almost 2 years!
When I went in there to attempt to replace that clip it had already melted into the block itself and was not able to pull it out even with the heat gun.
Is there any way to replace the entire block? And if so, what's involved I see it's a direct wire to the harness and or any ideas on how to get that clip out and the sources for that clip?
2011 c6 GS 4LT Fuel Pump Relay issie
