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Where is the underhood relay center?


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My 99 STS, engine replacement step 24 in my GM manuals is to disconnect the electrical harness from the underhood relay center. For the life of me, I can't find a picture in the manual anywhere of what it looks like or where it is.


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On my 96 one was behind the left (driver's side) wheel, under a cover. Remove the strut brace, remove the cover. Not sure if same on the 99.


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It's on the RH (passenger) side between the windshield washer tank and the power steering pump pulley. The cover is stamped with "FUSES RELAYS".

That is what you are seeking.


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Thanks Bruce/Jim.

I looked at that Fuse relay box, it appears to be 2 boxes stacked ontop of one another with clips on the outside. I lifted the clips, but the wiring coming into the boxes prevents me from separating them. Where exactly are the connectors the manual suggests I disconnect? This is part of dropping the cradle, so if there are parts not in the way I'd like to leave them be.

Thanks for answering the dumb questions ^_^ . There will be more...

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I was just in that area when I lowered my carriage. If you look behind the fuse relay panel there is a plug that I believe you can disconnect. You will need to disconnect all of the sensors and pull the wiring harness out. Here are a couple of photos that might help:

Bank 1

(1) IC Module

(2) IC Connector C2

(3) IC Connector C4

(4) IC Connector C3

(5) IC Connector C1

(6) Bank 1 Sensor 1 (Rear) HO2S

(7) ECT Sensor

(8) Linear EGR Valve

Bank 2

(1) Engine Oil Level Switch

(2) CKP Sensor A

(3) CKP Sensor B

(4) MAP Sensor (beneath dress cover)

(5) Engine Oil Pressure Switch



Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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