Here's the summary first because this is a long post:
Is there a newer Pinpoint Test QA 'No Codes/Codes Not Listed' for the 89
EEC-4 processor? My Motor Manual is from 1991 and covers 89 and 90.
Specificly QA5 which is the test for Self Test Output Short to Ground is the
one I'm questioning as to accuracy.
QA5 says measure the resistance of the Self Test Output at the Output Test
Connector to the engine ground. QA5 says it should be more than 10,000 ohms
but it doesn't make sense to me because this is the MIL light circuit and
the MIL light circuit is shared through the feed (common) side of the MIL
Light with all the guages and other lights in the instrument cluster. QA5
says if the resistance is under 10,000 ohms, (I have 35 ohms with the MIL
light installed and an open circuit with the MIL light removed), then the
problem is a short to ground in the MIL circuit.
I'm not saying this is wrong, I'm just concerned that the book might be
wrong because it is 15 years old and that may cause me to waste time tracing
down a 35 ohm short that might not be the problem at all.
Ignoring this and going to QA9 because the MIL is staying on with the KOEO
including while cranking, it tells me to go to ML1. This test says the same
thing as QA5 except it says check the resistance at the other end of the STO
at pin 17 at the breakout box to ground pin 40. Again it says if there is a
short to fix the MIL circuit.
Could the processor be causing this short to ground of 35 ohms with the MIL
light installed? This has me scratching my head because when I remove the
MIL bulb the STO circuit between the processor pin 17 and MIL light is fine.
The cluster looks fine, no burns and all the guages work. This leads me to
believe the test in my book may be wrong for the 88-89 with the MIL as
opposed to the 87 and lower which didn't have the MIL. This wouldn't be the
first time I've run across this.
Also would no Self Test Output (No Codes) from the ECA and a 29,000 ohm
resistance at the Fuel Pump Relay harness negative circuit to ground, the
one that goes to the timer in the ECA that grounds the relay turning on the
pump for 2 seconds with the KOEO be a sign of a bad processor? This 29K
resistance goes away when I unplug the processor. This resistance is causing
the fuel pump to stay on with the KOEO. It seems to be just enough to charge
the relay turning on the pump.
My heart tells me the processor is bad because the fuel pump is staying on
and I cant get any codes but I want to make sure my book is telling me the
right thing before I plug up a new processor and wanted to run this across
everyone here as well.
Here are the fine points and thanks::
It's an 89 Ranger with a 2.3 EFI and 8 plug DIS ignition that is blowing
black smoke and backfiring through the intake during WOT. It happened right
away like throwing a switch. The check engine (MIL) light is staying on all
the time including during cranking like the processor is in 'Falure Mode
Effects Management' or FMEM but without the accompanying code 98 which is
normally outputed when FMEM is in effect.
I tried to run a KOEO self test and no codes were outputed (no code 11,
nothing) along with no actuator/solenoid movement. I used an analog
voltmeter and it stayed at 12 volts, (no needle sweep). The STO circuit
I opened up my 1989-1990 edition Motor' Truck Engine Tune-Up and Electronics
Manual and after doing the usual checking of those pesky grounds and
connectors, sensor and output values, went to 'Pinpoint Test QA No
Codes/Codes not Listed' after being refered there from Quick Test 3.0. I did
QA1 Check For Voltage Ref. (Good at 5.0 volts)
QA2 Check Self Test Input (STI) Continuity (Good)
QA3 Check Self Test Output (STO) Continuity (Good)
QA4 Check HEGO Sensor Ground Continuity (This showed 1/2 ohm between
Breakout Box pin 49 and pin 40/60 at the box and I believe this would be the
same as going from the HEGO Ground to 'test pin 49 HEGO Input' because 40/60
1is grounded to the motor as well.) This should be fine. on to the next
QA5 Here is where the problem came into the picture as refered to in the
above summary. With the KOEO the STO circuit pin 17 at the ECA and the MIL
is fine with the MIL bulb removed but when I replace the bulb the resistance
goes to 35 ohms. i dont know if the instrument cluster, processor, or book
is at fault. With this in mind I continued on.
QA6 I skipped this because it is for the 'Intermittent NDS' requiring a
Engine Running Self Test and if no codes are outputed it tells you to go
right back to Pinpoint Test QA. On to the next.
QA7 Check Power Relay for Always On This test worked out fine. The power
relay cuts on and off with the key.
QA9 This ask the question 'is the MIL light aways on? Yes. This concluded
Pinpoint Test QA and sent me to ML1 which told me the same thing as QA5, fix
the short in the MIL circuit.
If the book is OK then where would a 35 ohm short be?
Thanks again, scratching head,