Help with rear fuse panel on 78 930
 

I have a 78 930 Euro. I'd like to identify the purpose for the three fuses in the rear fuse panel, because I may want to move them (or do away with them if they are not being used). I've done a search here and I've looked at the factory manual, and it's still not clear. Can anyone help identify exactly what each fuse is for?

As best I can tell from the factory manual, there's only one fuse that should be active, and that's for the rear-window defroster. But I haven't traced wires to see if that's true (or to figure out which fuse that is). It appears from my photo that the top two fuse holders are wired, and the bottom one may be a "blank."

One last question: There's a red relay shown as well. The manual (for a 77 model -- there's no data for a 78) says this is the "Air flow sensor/turbo boost pressure relay." Can anyone confirm that? What does it control? I don't understand the description. With EFI, I can probably dispense with it, if indeed that's what it's for.

You can see from the picture below that my modified air intake system interferes with the fuse panel and is risking a short circuit. That's why there's cardboard there as a temporary insulator. I figure if I relocate the fuses, I'll buy myself some room. But I don't want to do that until I know what I'm dealing with.

http://forums.pelicanparts.com/uploa...1145638915.jpg

On my Carrera those fuses are for:

Rear Window defogger/Rear wiper return
Heater Fan
Relay for Heater Fan

May be the same for you.

Reference: http://forums.pelicanparts.com/showthread.php?s=&threadid=274043&highlight=fuse+a nd+carrera

hello dont know much about that relay but i belive it is there to keep you from frying your engine with over boost it cuts the fuel pump when there is a over boost detected

The fuse panel on my 78 SC looks the same. In my case, the round relay is black and controls power to the rear heater fan. Power to the rear window defogger is on fuse 24 [top blue, 25 amp fuse]. The next one down, fuse 23 is switched relay power to the rear heater blower also blue and 25 amps. The yellow, 5 amp fuse on the bottom [ fuse 22] is fused power for the round heater fan relay solenoid. Again, this is for a none turbo 78. Hope it helps.

Folks,

Thanks. It was a good idea to look in the owner's manual! I never thought of that. I also don't have one. If anyone has a 78 930 owner's manual and could verify for me what the fuses were for in the rear fuse box for that year car, that would be great.

Unfortunately, it seems that the function of those fuses was different for turbo and non turbo cars, and it changed from year to year, so it's quite model-specific. For instance, the turbo does not have a heater blower fan on the engine as does the SC.

Being that I have only a rear defogger, and no rear fan, I may be able to ditch the other two fuse positions and move the one I still need. If that relay is for the overboost cutout to control the fuel pumps (sounds right), then I can ditch that too, because I have EFI now.

Thanks, everyone, for your suggestions.

Rob

Im pretty sure you still need the boost control it still dose the same job as before it really has nothing to do with your new injection system.

those fuses are rear window defogger rear wiper

Tony,

Thanks for the printout of the owner's manual. What year/model car is it from? What's odd is that it describes two relays and my car only came with one from the factory -- so I don't know what to make of that infomation.

If you're right that the two fuses are for rear window defogger and rear wiper (two separate fuses, I gather?), then it will be an easy job of relocating only one fuse. In my case, the wiper has been removed, but the defogger is still there and I'd like it to be operational.

Regarding the boost pressure cutout, with EFI (or at least with my DTA ECU), you don't need it. You can set the ECU to shut off the spark, pull the timing way back, or cut out the fuel pump relays at any prescribed engine condition. With most EFI systems, the fuel pump relays are directly controlled by the ECU. So, there's no need for a separate overboost pressure switch. That's just a CIS thang...

Thanks for your help.

Rob

a 79 930 euro i think we need a 3.3 expert on this one