Build of 1973 Datsun 240Z 

   Home Electrical 2016 update        

There are couple things that need to be addressed now that the car had its shake down. First is the bad mistake of routing engine pigtail harness together with engine bay body harness together through the same grommet in the firewall. Fixing this is very simple. A small 1.25" hole was drilled in the firewall then the cut area was primed and painted so that it would not rust. Grommet with water tail specifically designed for firewall application was slid over the pigtails. Later it will be taped to the harness to reduce the possibility of water going into the cabin after the harness is verified and engine is put back into the car.

Second is security relay and how its being energized. The way it currently is wired it is constantly energized where by constantly using power when the car is not running. A simple positive feed needs to be moved from battery source to ignition switch RUN / START positions so that it only is energized when the engine is running.

With the change of the instrument cluster gauges, all of the indicator lights had been removed as the original lights where part of the meters. Provisions for replacement of those lights where made during rewiring and a small cluster was made to me placed on top of the steering column but it was never finished.  Some of the Led's / indicators where dim possibly due to the plastic used or possibly simply due to the choice of the LED and resistors.

Idiot light pod needs to be finished and fix brightness of some of the Led's and also fix face plate of the pod. Will need to check OBD port and most importantly verify wire circuits

Engine harness
When the engine was purchased, all components seemed to be OK and as advertised. Everything was nicely wrapped and prepared for pickup. After installing the engine and trying to start it was discovered that the engine harness was out from 98 Camaro and the engine and PCM where actually from 02.  As it was probably 2 or 3 months after the purchase and maybe bit laziness it was decided to repin the PCM connectors and as it needed to be also modified to suit the needs of the car.
The car was running but it seemed that the engine was weak, plus the battery was never fully charged and needed to be charged up before taking it out for a drive. Hence probably was the sole reason why the lost of interest driving it last couple of years.
So as the engine was in the machine shop for rebuild, the harness was ripped apart to check for any mis wiring and following where found
   1.TPS low reference was wired incorrectly, grounded vs. wired to ref point on PCM  ( most
      probably cause of power in the engine)
   2. one PCM connection was missing (should have no adverse effect)
   3. ECT  connector looks like it was repaired at one time and rather then properly soldering it
       the wires where just twisted together and they did not seemed like they where making good
   4. Generator enable was going to one of the connectors from inside cabin I think its C210 on 98
   5. AC compressor clutch was wired incorrectly. As Ac was deleted this had no affect
   6. EVAP enable and solenoid where switched. Not necessarily the best mistake luckily there EVAP
       was disabled within PCM  but there was no return line back to the tank. Now the line was
       plumbed so that will fix the problem.

The re-pin of the harness had been updated and is available at this link

Never had the chance of labeling anything when it was installed first time so this time took some pictures of harness and each of the connectors. Click on the picture to see larger picture all the labels of connectors labeled.
C220 C230 C2xx  cabin connectors
C100 & starter,  C101 C105  connectors
Crank Posision sensor
O2 sensor connector
Left injectors & coil (even) connectors
Right injectors & coil (odd) connectors
Skip Shift Solenoid
VSS & Reverse lockout




Indicator (idiot) lights
As the new gauges don't have provision for things like turn signals, check engine light MIL light, high beam indicator and couple other  bulbs and not wanting to cut up the dash. A small pod was made out of plastic/fiberglass to go on top of the steering column. The idea was to put all of the indicators and have couple to be multi function by altering light color of the LED.
........ more to come

Security relay
The relay was originally wired in to B+ and switched ground. Problem with that is, when you forget to forget to turn the relay off with switch it constantly is enabled and draws power from battery. Its OK if the car is started every day or so to recharge the battery, But as the generator enable trigger was mis-wired and was sitting for extended period of times it discharged the battery to a point where it could not be started and actually damaged the battery as it was sitting at very low voltage.
To correct the problem the relay was rewired where the positive of B+ was switched to ignition switch Run / Start wire which solves the problem of draining and running the battery flat.  The main theory behind it is if the switch is in the off position the relay will not energize thus not provide the ACC power to the PCM in order to wake it self from stand by and start controlling the engine.  On the other hand if the switch is in the on position, and if the key is turned into run or start position the relay will energize and provide power to PCM.  The switch acts as a kill switch so that if someone tries to start the car and the switch is shut off they will not be able to start the engine.



All content is copyrighted 2016