OK, I admit I am not a rocket scientist when it comes to the newer electronic EFI junk, but I think I can even recognize bad news when I see it. Someone tell me differently...
So my rig has had a starting problem for awhile. I took the time to go through all of the electric junk from the batteries forward, cleaning off all the connectors, replacing grounds, etc., etc. all the way up to the the electronic stuff. While I was doing this, I also took the time to replace all the fuses and all the relays. It still didn't start, but not for lack of juice.
Next I decided to go through the whole fuel system, checking the fuel pump, replacing the filter, draining the tank, blowing out the fuel return line, etc. Now I have a handy dandy access panel cut through my truck bed for fuel pump access and know that the WalPro 190 fuel pump I stuck in there 6 years ago works like a charm..
Anyway, I was now down to the electronics...(did I mention I know dick about them?)..not to mention the fact that to get to the ECM and have at least a little room to work, I had to remove the seat, the speaker, half of the dash, the glove box, the heater motor, six years of under dash dust (tube doors half the year make for a nice mess. I was surprised that I didn't have moles living under the dash..)...you get the picture..
I decided today to go down to the local Checkers and make use of their rent a tool program. I grabbed an OBDII reader, sans instructions, hooked it up and the very first OBDII code I have ever read in my life was this one:
DTC P1600 ECM BATT Malfunction
A03375
Battery
2
R/B No. 2
E5
ECM
BATT
2
B–Y
15
IF1
W EFI
16
2
1
B–Y
DIAGNOSTICS – ENGINE (5VZ–FE)
DI–279
2002 TOYOTA TACOMA (RM921U)
DTC P1600 ECM BATT Malfunction
CIRCUIT DESCRIPTION
Battery positive voltage is supplied to terminal BATT of the ECM even when the ignition switch is OFF for
use by the DTC memory and air–fuel ratio adaptive control value memory, etc.
DTC No. DTC Detection Condition Trouble Area
P1600 Open in back up power source circuit
Open in back up power source circuit
ECM
HINT:
If DTC P1600 is displayed, the ECM does not store another DTC.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using hand–held tester or OBD II scan tool, as freeze frame data records the engine
conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the
vehicle was running or stopped, the engine was warmed up or not, the air–fuel ratio was lean or rich, etc.
at the time of the malfunction.
DI0SG–15
A18845
BATT (+)
A18222
EFI Fuse
R/B No. 2
DI–280
DIAGNOSTICS – ENGINE (5VZ–FE)
2002 TOYOTA TACOMA (RM921U)
1 Check voltage between terminal BATT of ECM connector and body ground.
PREPARATION:
Remove the glove compartment (See page SF–58).
CHECK:
Measure the voltage between terminal BATT of the ECM connector
and the body ground.
OK:
Voltage: 9 – 14 V
OK Check and replace ECM (See page IN–28).
NG
2 Check EFI fuse.
PREPARATION:
Remove the EFI fuse from the R/B No. 2.
CHECK:
Check the continuity of the EFI fuse.
OK:
Continuity
NG Check for short in all harness and components
connected to EFI fuse.
OK
Check and repair harness or connector between
battery and EFI fuse, and EFI fuse and
ECM.
Me again...Since I replaced the EFI relay with a brand new Toyota unit and have power to the fuse box, then I am going to assume that that part is OK, as well as all the rest of the fuses and relays. I removed the connectors from the back of the ECM and there was corrosion(?) on some of them. I used a quality electronics parts cleaner to remove this on both the male and female parts, also removing the cover (hell, what did I have to lose at this point?) from the ECM and cleaned the board the same way I would do a regular computer MB. Let it dry, stuck dielectric grease on all the connectors, plugged the OBDII scanner back in, turned the key on and got the same code....Surprise, surprise, the rig didn't start then either...
So, being the non electronic wizard I am, I am assuming the this equates to the Windoze "Blue Screen of Death" and pretty much sounds the death knell for the ECM.
So, if there is anyone who knows OBDII codes and electronic EFI systems well, please speak up as I could use a little input before shelling out the big bucks for a new ECM...
Thanks in advance.