on page 128 in the Haynes manual, Figure 9.21, there is a pic of the relay board with fuses numbered 9 and 10. 9 is a 15 amp fuse, 10 is a 30 amp. does anyone know which fuse, 9 or 10, corresponds to the fuse S13 in track 93 on the schematic on page 181? the schematic is for a 74 model.

the page numbers for different printings may be different from the ones in the question above but the figure 9.21 probably is the same figure (maybe different page number) and the 74 schematic probably is the same schematic

another way to answer this question is to figure if the fuel pump would use a 15 or 30 amp fuse.

thanks!

None of them do. S9 would be the fuse corresponding to fuse #9. S13 is, I believe, one of the fuses on the relay board. Check the relay board diagram (also in Haynes) and look for which wire colors connect to the fuse; check the two diagrams against each other to see if the fuse in question is the front one or the back one.

--DD

don't go away ... the reference to 9 and 10 are the haynes numbers identifying components for Figure 9.21, not the fuse box fuse numbers, for the 2 fuses on the relay board, thus there are no wires going to the fuses for color check.

yes, i'm trying to find out which fuse on the relay board is S13. the haynes figure 9.21 doesn't distinguish as far as i can tell.

of the 2 fuses on the relay board, one of them is before (?) the fuel pump relay and is therefore, in the fuel pump circuit and i have yet to find what the other relay board fuse is for.

OK, i think i answered my own question (where is "egg-on-face" smilie?) but will post here in case this helps someone.

S13 is the fuse on the relay board that is toward the rear of the car, or, viewing the relay board from the drivers side, the one on the right. this was determined by looking at the schematic of the relay board in the electrical section of the workshop manual (would also be in Haynes) and seeing that, duh, there is nothing connected to the fuse on the left (so why is there a fuse in that holder? spare?) and the other fuse, figure number 91 for a 25 amp fuse (hmmm, Haynes says one fuse is 15 amp and the other is 30 amp) and the legend for the figure is "Fuses for rear window defogger, heater fan and", ta-daa, "fuel pump"

This might help Jim. Just to cloud the issue it shows as 25 Amp.

I don't know who did this diagram - can't remember where I found it. Maybe Brad Anders? Whoever I thank him/her. It has been really helpful to me.

OK, in my Haynes manual (printed in 1976), for 73-76, fuse noted by 9 in Fig 9.21 is not used.

Fuse noted by 10 in Fig 9.21 is fuse S13, page 175, current track 94 for 74; or fuse 13, page 181, current track 94 for 75. Fuse S13 powers the blower motor and fuel pump.

Follow straight down current track 94 from S13 and see relay J14 which controls blower motor V4 also on current track 94.

Note that just below S13 is a connection of 4 wires. The wire to the right goes to relay J17 which powers fuel pump motor G6 on current track 96.

Hope this helps.

Spoke

thanks for the help! it's good to know and confirm things.

The forward of the relay board fuses connects to pin #9 in the right-rear connector on the board. That pin is unused in most or all 914s to my knowledge. That fuse is fed from the same "switched power" source that runs to the coil and that also operates the "power supply" relay for the D-jet.

It does make a nice spare...

--DD

I thought that other fuse was for the optional rear window defroster.

nope ... the first fuse (8A) is not used at all, it supplies power to pin #9 on the connector for the engine harness, which is not used.

it has been speculated that the first fuse was used on sportomatic cars, but i have never seen one in person, so i can't confirm that.

the second fuse (25A) also fuses the rear window heater, if present.

in fact, the only relay not fused by this fuse (and not fused at all) is the second from the front, the relay for the power supply.
all other 3 relays are fused by the second fuse ...

Andy

so ... what is, where is, what does it do... would you shed a little bit of light on the "power supply"

the "power supply" relay (#74, second from top) get's 12V *directly* from the battery through pin 12 on the main harness connector.
from there, the 12V is routed to the FI brain, through pin 1 on the 4-prong FI connector.

so, the relay supplies the FI brain with 12V ...
Andy

PS: from haynes manual, page 144 through page 164, depending on the year of your car.
altough the relay board seems to have undergone only very minor changes over the years ...