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Basics ... back to the beginning and go through the motions logically, don't allow yourself to rabbit hole and get distracted - lay out the test plan and stick to it.
Grants no start doc is a good place to start. If you have spark then the chance that this is the ignition module is very very slim. That the car runs on starting fluid confirms the fuel diagnosis but not the why part.
There should not be ANY power at the resistor pack - the injectors are grounded via the resistor pack.
First methodically clean things up, all connectors - remove the resistor connector and get the contacts cleaned, verify continuity as appropriate from the resistor pack plug to the injectors with the ECU disconnected - the colours provide a clue but pins 1 (Orange/Blue - Inj 1A 3A 5A, 3 (Orange/White - Inj 2A, 4A, 6A), 4 (Orange/Grey - Inj 1B 3B 5B), 6 (Orange/Green - Inj 2B, 4B, 6B) are the ones you need to target. If you flick each to ground you should hear a click if the injectors have the 12V indicated - DO NOT hold to ground or you will burn the injectors out you are simulating a pulse. Do this before condemning the ECU. The ECU grounds via pins 1, 2, 16, 17, 34, 35 I don't know how the internal circuits utilise these pins - they may be common but I'm not sure. For whatever reason the injectors seem to ground on 3 pins for each set of three, only one connection of these three is via the resistor pack, and I have no idea why this would be so. This will confirm the injector harness etc etc, do you have the wiring diagram for the car ?
The screened wire has been the source of many alcohol abuse sessions - worst case run a bypass from module to ecu - this will at least narrow things down.
Don't get disheartened things can get real frustrating when electrics start playing up. I chased a fault for weeks and it turned out to be a fuse box issue - but everything tested fine ...
@BenKenobi: At the resistor pack, there are 8 wires. 4 K/B wires and the 4 O/blue; O/white; O/grey and O/green.
From my understanding the the 4 K/B are 12v wires and the 4 Orange are ground. So maybe I am not understanding this circuitry.
You are saying that I should not see any voltage at the resistor pack?
I am not doubting you( this is the 1st V12 I have ever worked on) in the least, but I need to go back to the car and recheck the terminals at the resistor pack.
Are you saying that with the 'key on' I should have no voltage at the resistor pack? If so, I have a huge problem because I am sure I saw voltage there.
Going back to the drawing board.
My understanding of the drawings and this circuit is that there shouldn't be 12V there - Power here comes via the injectors I'm a dummy (it's late - my excuse any how) see next post though. The +ve for the injectors comes via a relay - numbered 312 on the drawing
I you saw voltage there it is coming via the injectors - if you disconnect the injectors you will lose the volts - there should be no ground on the other side of the resistor packs - but this part I don't understand as there are three paths to ground according to the drawing - perhaps the ECU switches all three but requires only one to be regulated.
Here is my understanding. Please correct me if I am wrong.
From the ECU I have 4 wires going to the Resistor pack.
Injector Hold Pins:
Pin 11= K/S - to resistor pack > O/S from resistor pack to injectors 1; 3; 5; B
Pin 29 =K/G - to resistor pack > O/G from resistor pack to injectors 2; 4; 6; B
Pin 12 = K/U - to resistor pack > O/U from resistor pack to injectors 1; 3; 5; A
Pin 30 = K/W - to resistor pack > O/W from resistor pack to injectors 2; 4; 6; A
Is my interpretation correct?
Correct - I wasn't reading correctly - the 12V will pass all the way through the injectors - it will not be able to complete a circuit and fire until the ECU closes Pins 11, 12, 29, 30 to ground - and I think the other associated pins too - really don't know what those additional ground paths provide - seems a bit daft to ground only one - and why three ?? either way it clearly works as wired so I won't get too stressed if you don't.
More of my understanding of the Injector circuitry:
I guess that this is on the 8 pin harness.
INJECTOR 'ON' circuits
from the ECU:
Pins 8; 9; O/S > injectors 1; 3; 5; B
Pins 27; 28 O/G > Injectors 2; 4; 6; B
Pins 13; 14; O/U > Injectors 1; 3; 5; A
Pins 31; 32; O/W > Injectors 2; 4; 6; A
Is the above correct?
If the drawing is correct it is - I really don't know what those do though - seem surplus - don't know what the resistor pack is achieving but I know it has to be there. Check the continuity of the white trigger wire from ign module to the ecu connector (pin 18) - not sure your current meter will make that easy - you need to ground one end then measure the resistance to ground - (ignition off) - or you can measure the voltage on pin 18 which ever works for you.
Ben
My entirely non-expert understanding is that the resistor pack protects the injectors from burnout, it takes a belt of current to open them, but nothing like so much to hold them open, the resistor pack somehow achieves this reduction.
All that wiring is how I also understand it. RARELY gives any issues, apart from the grubby multi pin connection, which has been cleaned.
I have run the wire over the roof on a few, and I used normal OLD speaker wire, and took the time to remove the thin signal wire at terminal 18, so I had e "clean" path, Amp connector to #18. NO risk of interference with that shield or the thin inner core.
The cars all started just fine, and that concluded:
ECU is fine
Resistor Pack in fine
Shielded wire is screwed, SOMEWHERE
On the Blue snot box I had, I simply ran a normal wire along the ECU Vac supply pipe/hose under the car, NOT EASY, but easier than looking for a shielded wire issue, and that fixed it. That was 20+ years ago, and he still Daily drives that car, so not so fussy system after all.
The Red Devil, cause of my drinking issues, eventually found to be the wiring from the CTS, via the ATS, and the TPS, across the rera of the engine and around the Brake Booster (RHD), and out through the grommet,was all shorted. The fiddle factor was the eventual "tool" that found it, so the engine bay got 100% rewired, and most of the electrical items moved out of the engine bay, HUGE job, but so sweet at the end.
Pardon me if this has been covered.
The TPS snapping open to activate the Injectors should still occur, even with the shielded wire broken. Hence the talk of engines running for that few seconds on teh squirted fuel from that operation, but stalling due to lack of pulse to pin 18.
Last edited by Grant Francis; 10-13-2021 at 03:03 AM.
Grant, Greg and BenKenobi:
After repairing the "DREADED WHITE WIRE" in the engine bay, (I removed approx 8 inches of brittle wire, cut and rolled the shield back and used shrink tubing to hold it in place).
I tested the newly repaired wire from the engine bay to Pin 18 and I had continuity. I tested pin 18 to ground and no shorts in the system. The shield is grounded properly at the ECU.
On my car the shield has a separate ground that goes under the battery ground wire. All the other ground wires were removed, cleaned and reinstalled.
Using an Analog voltmeter (not very accurate) I see the voltage on the "DWW" drop and rise as I crank the engine. Maybe that is the pulse? I do not know.
The K/B wires from the main relay is supplying voltage to the injectors.
My new injector harness was done as follows:
A1; A3; A5 + connected to Pin 2 on the 8 way connector
A2; A4; A6 + connected to Pin 3 on the 8 way connector
A1; A3; A5 - connected to Pin 6 on the 8 way connector
A2; A4; A6 - connected to Pin 7 on the 8 way connector
B1; B3; B5 + connected to Pin 8 on the 8 way connector
B2; B4; B6 + connected to Pin 4 on the 8 way connector
B1; B3; B5 - connected to Pin 1 on the 8 way connector
B2; B4; B6 - connected to Pin 5 on the 8 way connector
Presently I have the connector from A1 with a Noid light connected to it.
I am going to look at the TPS again because I am not hearing the injectors click when I snap the throttle open.
I will report the results tomorrow.
The reason I included in my last post how I wired up the homemade injector harness was that I was not sure whether it was wired correctly to the male plug because there were no indications on the plug of which way the terminal numbers ran. I numbered it as indicated in the attached photos using an electrical schematic so I need to make sure that it was done correctly. connector to injector harness other side of connector to injector harness
The other point I would like to add is if I ground the "DWW" with a test light and the injectors click, that would mean that the "DWW" circuit is doing what it is supposed to do.
Except the ECU is not firing the injectors when the engine is being cranked. Test light lead connected to ground. Test light tip touching the "DWW" connector.
Ben
Great diagram. Just so I am sure: the plug is the plug on the end of the injector harness, not the loom?
and
I am to imagine I am the wire going into the plug, NOT looking at the connector side of the plug?
I wired it up looking at the male half of the plug that goes to the injector harness. The wires shown in the photos I posted go to the injector harness.
The female side of the plug is on the loom.
With the key "ON" and the injector harness disconnected from the injectors, I get battery voltage at the 8 wires at injector plug and at the 8 wires on the connected resistor pack plug.
Grounding the individual orange wires at the resistor pack does not make the injectors click as BenKenobi suggested.
10-11-2021, 01:47 PM
