kabz

1988 Rx-7 GXL with Recent New Fenders - Not startingWelcome to my new build thread. Traded my blue 87 Sport for a 88 GXL with a beautiful interior and only 71k.
However, not running due to an electrical issue.
Few pics...


Pretty clean on the back


Super clean interior


Even the vents at the back are still there.

Downside - Not Running
However, as good as the interior looks, and mostly works, the engine will crank over, but there's no power to the fuel pump, coils, injectors or indeed the main relay.
After a few days of casting around, I identified the (possible) issue. The screw pictured is holding the fender liner in. BAD bodyshop!!!!


Tech screw into engine harness - Car had a minor wreck and new fenders fitted


Various damage

On-Going Troubleshooting
Having repaired the identified damage, I'm still showing shorts to ground from the battery cable into the engine fuse box. Car wiring is new to me, so bear with me. I think the next step will be to pull all the fuses, verify no short then on the main battery cable into the engine fusebox, and then identify what circuit and wire color is still shorting to ground.
There's a lot of wires, but it's doable.

kabz

I haven't seen a thread that covers basic electrical trouble shooting, so I'm going to make the next few posts about my process for hopefully fixing the electrical short in my harness.
The above pictures include an obvious breach into the harness, but for the sake of argument, I'll ignore that, and consider that the short could be anywhere, which in fact it could be.

Ok, So You Have an Electrical Problem
What are the symptoms?

• Engine fuse blows when ignition turned on
• Main relay doesn't turn on
• No power to coils, injectors etc.

Troubleshooting

• Look for obvious issues - in my case, I found a screw that had burrowed into the harness

Repair

• I removed the clutch master and unwrapped the harness around the damaged area
• I cut, stripped and crimped new sections of 12 AWG wire into B/G and W/R wires, and 16 AWG into B/W.
  
  
  

Symptoms

• Problem is still not fixed, ground is still connected to the main positive wire into the engine fuse box (short)
• However, engine fuse didn't blow with ignition on, so likely there's only a small cable carrying current to ground
• Both cables into main relay show a sort to ground B/G and W/B, worse than before, but probably due to me plugging in all cabin fuses.

Troubleshooting (ToDo)

• Remove all engine fuses (upstream of issue), and check downstream circuits,
• Possibly remove all cabin fuses and look for shorts to ground at inputs (upstream) and outputs (downstream) into the cabin fusebox

Definitely a good idea for me to stop and write some of this down, and consider how to go forward.

kabz

Ok, so I've started troubleshooting again. Here is the current situation: [Car is a 1988 GXL no-abs manual N/A]

• I've repaired the obviously broken wires in the harness next to the clutch master
• No grounds appearing on engine fuse box [guess that's a step in the right direction!]
• The only known modification is that the p/o added a clutch inhibit switch in the dash as an override for the non-working one on the clutch [starting to think this may be an issue... lol]
• With all engine fuses plugged in, and cabin fuses plugged in (and I believe good)
  • No grounds on engine fuse box
• The following grounds appear on the F-31 big ECU connector
  • L/B 20kmile switch
  • B/R shift light
  • BR water temp
• The following grounds appear on the EM31 medium ECU connector
  • B
  • B both grounds I believe
• The following grounds appear on the EM-03 small ECU connector [clutch override switch closed]
  • B/R clutch / starter interlock
  • B/L clutch / starter interlock
• Investigate clutch wiring - ok I think, see notes below.
• At the engine fuse box with all engine fuses pulled
  • BTN B/L 60A is always a short
  • B 80A is a short with ignition ON only

I guess the next think to check is the clutch inhibit override added by the P/O. The car was able to crank over, but not sure what other circuits may have been affected.

Clutch Switch Wiring
Into the starter interlock switch:
B/G is grounded - not a short as ignition is off, hence the (1) for grounding point on the power source tramlines ____ 1 (1) ___
B/R is ok


B/R and B/G into the switch the p/o wired [Corrected for colors here]
Y/L and B/Y into the switch the 'unpresses' when you hit the clutch.

Any ideas? Well nothing, I'll keep going.

• At the engine fuse box with all engine fuses pulled
  • BTN B/L 60A is always a short
  • B 80A is a short with ignition ON only

Let's see what is shorting out BTN. Ok, after setting up my multimeter:

• BTN B/L 60A goes to ground with Room fuse - controlled by driver door switch - guessing this is ok
• B 80A goes to ground with Meter fuse - Ok?

Thinking about putting the battery on, and seeing where we are.
Ok, put the battery on, and the following are working:

• Radio, power antennae, speakers,
• ECU is up and sending diagnostics through the diagnostic port
• Lights, wipers.

What's not working:

• Fuel pump ... not sure what all I have disconnected
• Some of the warning lights