Square one is fuel pump. The two round one's are MAF power and Burn-off. On the round plug relay cars, it has been stated the two are interchangeable (same relay).

GD

 

Zackly:

A relay is just an electrically operated switch. From another thread; this one was re. the fan motor relay, but the principle is of course identical in all cases. Only difference in your case is that the ECM is commanding the relays rather than a temp switch.

IIRC the relays are nearly identical to begin with; only difference is, one has 4 terminals and is a form A ("make" contact only), and the other has 5 which is a form C ("changeover" contact). The 5th terminal makes its connection to the "common" terminal only when the relay is not energized and "breaks" when it operates, and doesn't matter to the 4-terminal circuit. Therefore you can use that part # in both places.

I suspect that the relay that's just hanging there used to be mounted like the others, in that empty spot.

 

 

The pigtail connectors can become borked over time. Your style looks newer...on mine, some of the wire jackets were starting to expose and a few of the wires were really loose in there. But, even with the newer style, get up close with them and make sure the connectors are still viable.

Mentioned above, MAF power and MAF burnoff relays are interchangeable. Swap to see if one makes a difference. Both of mine were bad and I ended up replacing both. It's kinda weird that two would go out, but, these cars are getting really old now.

That one should be screwed into the hanger for the relays...my guess is the holes in the hanger stripped, so at one point it was nailed to where it now sits to make it secure. If you want to make it original-looking, just use a longer bolt with a nut on the other side.

 

 

 

The original relays are different - I had my connectors swapped and that's what led to the code 36 in my case. I swapped them around and the code never returned. Also there are threads around here with pictures detailing that insides of the relays and they do have different resistors inside. Now it is obviously the case that only one of the two circuits needs the correct resistor (or doesn't need a resistor) and the other circuit will work with either relay - so if you get lucky and get the correct burn-off relay it appears that one will also work for the power relay but perhaps the voltage isn't quite right on the MAF power (or? Does the power relay have the resistor and having the wrong power causes the burn-off function to be out of range?!?). Does that mean it won't run? No because the computer adjusts for MAF output on the closed loop end of things. It may not read correctly when cold and I would suspect there would be some cold warm-up mapping issues. They may be insignificant..... this is all speculation and it may not matter in the least in practice but I can tell you FOR CERTAIN, that the relay ARE different, carry different part numbers from GM, and there is a reason for it. They wouldn't design it that way if all they needed was a generic relay - it would be cheaper obviously to use off the shelf parts not custom one's with carefully chosen resistors inside.

GD