Gen2n3

iTrader: (1)

Yesterday I re-examined why my 15A Meter fuse keeps blowing. And just as before I'm left scratching my head in wonder and amazement! For a history, feel free to check out this link:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/blowing-meter-fuse-564005/

Keep in mind all wiring harnesses are disconnected from the fuse box (even the fuse box is removed from the car) and the instrument cluster & heater control is also removed from the car.

Systems checked: (each pin to GND)
B-2: Coolant Fan System - JB-04 Pin I = SHORT
C-1a: Instrument Cluster and Warning Lights System - JB-02 Pin G = Open
D-2: Rear Wiper and Washer System - JB-03 Pin M = Open
F-1: Turn & Hazard Warning Lights System - JB-04 Pin G = Open
F-3 Stoplights/High-Mount Stoplight/Back-up Lights System - JB-07 Pin M = Open
I-1: Rear Window Defroster/Cigarette Lighter System - JB-03 Pin M = Open
J-3: Power Antenna System - JB-03 Pin M = Open
J-4: CPU/Theft-Deterrent System - JB-07 Pin L = Open ; JB-09 Pin P not tested - Part of Fuse Panel and is removed from circuit
Q: Cruise Control System - JB-02 Pin G = Open

Variables:
Just to remove all doubts, and despite my FD being a Manual trans I also checked:
H-1: EC-AT Control System - JB-07 Pin M = Open and JB-04 Pin I = SHORT ; Then I looked for H1-01 Pins 1N and 1P at the ECU; which I couldn't find since this schematic is for Auto Trans. With the exception of JB-04 Pin I as indicated on B-2 system H-1 system is good.

Y- Ground Points (Joint Connectors) were not visually inspected.
Cooling Fan Relay harness has been cut back exposing the harness up to the main trunk. Visual inspection and manipulating the Front Wire harness proved no break in continuity at JB-04 Pin I or at each Fan Relay B/Y wire input.

Questions:
What causes JB-04 Pin I to short to GND?
Could it be possible the B/Y wire that connects between JB-04 and the Cooling Fan Relays be shorting to the ground points?
Where would be a logical place for the B/Y wire to short?
Would even a new Front Wire harness fix it?

Your input and help is greatly appreciated. It would be a near miracle to get my FD assembled again and running properly!

Thanks,
George

nashman69g

iTrader: (3)

If u have the fan wiring upgrade here...Check over the wires as the update didn't always get wired this way...Try narrowing the problem down by disconnecting the relays and see if one could be causing a problem.

gracer7-rx7

iTrader: (16)

I recently had a similar problem. I think you have a wire shorting out somewhere.

In my case, it was the 60A fuse for the cooling fan. A few days earlier I had readjusted the position of my radiator in my FMIC setup. Turns out that I had pushed the rad back just a wee bit too far and crimped the wires on the back of the fans to the cross bar that supports the SMIC.

Could very likely be that you crimped a wire somewhere around the various little jobs that you did before this happend. Start backtracking and maybe removing stuff till you find it.

Gen2n3

iTrader: (1)

Nash, my cooling fan system is not wired for the update. I still have each B/Y wire going to each relay. Thanks for the schematic!
gracer7, with the excetion of my rad, just about everything is yanked out of engine bay. What wires run across the cross bar for the SMIC? The only wire close to that should be AC pressure switch.

nashman69g

iTrader: (3)

try disconnecting all relays and plug in one at a time and if it blows when connected you can just follow that wiring. If it blows before any are connected then it's the wiring before each relay.

Gen2n3

iTrader: (1)

Nash, with no relays connected I still read a short. I also cut back the harness backshell and found the splice point for all 4 B/Y wires. Everything looks good. I believe the problem is within the wire harness itself. The question is how far into the harness is it boogered up?

nashman69g

iTrader: (3)

thats might be a PITA...If u can afford it get a new harness; If u are straped for cash then strip it all the way back untill u find the damaged area.

Gen2n3

iTrader: (1)

either way, i'm not looking forward to a) hacking into wire harness or b) replacing harness.

nashman69g

iTrader: (3)

u may find other issues if you find the wire that shorted. It could have cause damage to other wires that might be hanging on by a thread! Have fun with that. Let us know what u find.

Gen2n3

iTrader: (1)

interestingly enough, this is the only system affected. Everything else appears to work.

nashman69g

iTrader: (3)

I know this is different but my radar detector fuse kept blowing on me. Come to find out, after cutting open the wires, the + side was fried the sheathing had melted causing a short to the ground side. I had to replace a good chunk of it. It works great now. I know everthing is working but like I said the short could have caused damaged to other wires surrounding it. Just inspect the area were your damage is just to be safe.

Marshall

Gen2n3

iTrader: (1)

Marshall, thanks for the tip! Looks like a project for the Turkey Day weekend!!