Ignition module should be replaced at distributor , should be able to pick up one at loacal parts store or take it to parts store and have it tested numerous cycles for failure and a lot less expensive.
I have found Toyota wiring harnesses to be terrible. I'd try the following: jumper wire power directly from the battery to the ECU & jumper a ground right from the battery to the ECU & see how it starts. If this makes a difference then you have a wiring problem. If it doesn't, try advancing the timing while cranking. If advancing the timing makes starting easier, then it's an electronic part beginning to fail. I have found that advancing the timing usually will let the engine start, but then it runs terrible because the timing is to far advanced. Once the timing is put back to spec, the engine starts hard or not at all. I have found this a few times. Replacing the distributor fixes the problem- good luck.
Frame grounds are as solid as can be. I know I am losing power or ground to my ECU during cranking. I just need a schematic and I can fix this truck. Spark good, LP lockoff energized, there are 8 wires going to the throttle and it is impossible to backprobe at the throttle. There is another 6 wire connector at the LP regulator that I am unfamiliar with its purpose. Schematic please!
Thanks
Just to make sure. I remove the ground cable and grind/file the paint/frame and cable to bare metal. Then connect the cable. Not trying to beat a dead horse but this problem caused me to age a few years. Looks good but it breaks down under load.
Anybody have a schematic for this truck?
ltrm812 at gmail dot com
Just got back to the jobsite this morning, frame grounds are solid, zero voltage drop on the B- side of things. tested at the frame near the ecu and the one near the left step all are good. the only place I get a voltage drop is on the engine itself during cranking but it is only.2 volt. I ran a B- jumper to the block just in case, no change.
I usually add an extra ground cable. That works the best.
Check the ground on the inside of the left frame. clean to bare metal...... id almost put money on it.
There was an issue with the ground Cables/Straps not getting proper conductivity - Just a thought