Strange Connector in Fuse/Relay Center

KANT NGUYEN

MEMBER
1995 GMC SIERRA
5.7L
V8
4WD
AUTOMATIC
200,000 MILES

Hi!
Man this truck is killing me. Bought as a project and im sorting thru a lot of hairy wiring to get the fuel pump to spit ultimately. However, please take a look at this pic and let me know if the gray 2 wire connector should be there. The image is the backside of the fuse/relay panel under the hood and the bottom is at the top so the fuses in question are initially on the top right, battery 50A and Lighting 50A and they are jumped to the EcmB and RR defog buses with the 10g 2-wire connector via main bus. Is that supposed to be there or is it retarded? I have so many electrical issues it seems like this is the root because it would give full time power things that shoukd only have key on run or accy position. Any help would greatly be appreciated. Steve

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4 Replies

HMAC300

MECHANIC
48,601 POSTS

ECM-B fuse powers relay and gray wire goes to pump. ECM-B is an orange wire leading to oil pressure switch and pump relay in box. See picture black/white to ground left hand top of engine. Dark green to PCM. The gray wire for pump only runs to oil switch and pump/relay and PCM telling relay to turn on.

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Tuesday, November 29th, 2016 AT 4:18 PM

KANT NGUYEN

MEMBER
6 POSTS

Whoa! You are on to the crux of the matter here and I did not even mention the fuel pump issue, nice. Okay so then are the gray (86) and black/white (30) wires switched on the fuel pump relay circuit? I have been trying to find this out everywhere! So, to clarify, the gray wire needs to be in the thirty position so that it matches up with the gray wire in the pump connector, right? Essentially moving the black/white wire to the 86 position.

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Tuesday, November 29th, 2016 AT 5:24 PM

KANT NGUYEN

MEMBER
6 POSTS

Oh sorry, but to clarify the bulky gray plastic two wire connector at the bottom that has the two orange wires connecting fifty amp maxi-fuses to the top and middle row sets of twenty amp fuses, does that belong there or is it doubling up on twelve volt current? Should it be removed?

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Tuesday, November 29th, 2016 AT 5:28 PM

HMAC300

MECHANIC
48,601 POSTS

ECM-B fuse has two orange wires to it so leave it alone. To avoid further confusion on diagrams and excommunications why not rent the book on here they let you have access for a week and you can print everything out instead of you contacting me to print out certain things because the size is way to big for me to do to get the full picture. The picture of the underhood box that I am sending shows most of large amp fuses but the bar you see could be wires that are the same color like red to all of one side then red to other connector.

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