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Chevy Blazer relays

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Old Aug 26, 2025 | 03:31 AM
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Default Chevy Blazer relays



I have 1999 RHD Chevy Blazer. I need to identify the electrical relays
and confirm the orientation of each one. The photo shows to fuses and relays
Everything appears to work except the engine will not start.
I now live in France and my friendly garages are frightened of the car!!
Thanks for your help
 
Old Aug 27, 2025 | 04:38 PM
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Page 6-62:

George
 
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Old Sep 23, 2025 | 05:57 AM
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Thanks for the info regarding the 1999 Manual - very useful,

What I am looking for is the detail regarding the orientation of the relays. Surely they only locate one way in the socket.

Thanks in advance
 
Old Sep 23, 2025 | 09:47 AM
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Originally Posted by BooTs
Thanks for the info regarding the 1999 Manual - very useful,

What I am looking for is the detail regarding the orientation of the relays. Surely they only locate one way in the socket.

Thanks in advance
I have had the same thoughts.

Then I looked at the pin-outs of the relays and saw that for the 4-pin ones, the orientation doesn't matter. This was because the paired pins, one set for the coil and one for the switch, are on opposite corners of the rectangular base of the relay.

Because it is a rectangle, there are only two orientations possible, 180 degrees from each other. The result is that the paired pins are always in the same opposite corners, e.g., top-left with bottom-right and top-right with bottom-left, no matter which of the two possible orientations is used.

The reason this is works is that there is no polarity for these paired pins, i.e., current can flow either direction between them.

The orientation of the blades of the pins also enforces the constraint that there are only two possible orientations for inserting the relays.

However, I would imagine the engineers used a rectangle base instead of a square because they knew that someone would try to install a square-based relay only 90 degrees off even though the blades of the pins would not be aligned with the receptacle.
 
Old Sep 23, 2025 | 09:51 AM
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Originally Posted by christine_208
I have had the same thoughts.

Then I looked at the pin-outs of the relays and saw that for the 4-pin ones, the orientation doesn't matter. This was because the paired pins, one set for the coil and one for the switch, are on opposite corners of the rectangular base of the relay.

Because it is a rectangle, there are only two orientations possible, 180 degrees from each other. The result is that the paired pins are always in the same opposite corners, e.g., top-left with bottom-right and top-right with bottom-left, no matter which of the two possible orientations is used.

The reason this is works is that there is no polarity for these paired pins, i.e., current can flow either direction between them.

The orientation of the blades of the pins also enforces the constraint that there are only two possible orientations for inserting the relays.

However, I would imagine the engineers used a rectangle base instead of a square because they knew that someone would try to install a square-based relay only 90 degrees off even though the blades of the pins would not be aligned with the receptacle.
This. 5 pin versions only go in one way.

George
 
Old Sep 24, 2025 | 05:32 AM
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Thanks guys. I have 2 problems, first - battery drain caused by faulty control unit for ventilation system. Second - after starting to check fuse relays car refuses to start. All instruments , electric windows and door locks, starter motor all work but no ignition????
Any ideas guys
Thanks
 
Old Sep 27, 2025 | 09:16 AM
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You need to check for spark during cranking and if spark is good, do the fuel pressure leak down test.

George
 
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