Electrical Issue...Need ECM? (1 Viewer)

[ravencr]

Hey guys,

I was driving my '97 LX450 a month or so ago, and all of a sudden it stopped running, sort of like when a fuel pump dies it was a slow shutoff as I coasted to a stop.

So, the truck will crank over like normal, but nothing fires up or starts. I pulled one of the return fuel lines to see if any fuel was cycling, but nothing was coming through the return line.

I was going to mess with it, but decided I didn't have time, so I took it to a shop to get the fuel pump replaced, assuming that was the culprit.

So, they found the fuel pump was fried out, so they replaced it. Then, they discovered no power to the fuel pump from the ECM. So, they replaced the EFI relay. The EFI relay is getting power and ground power, but no switch power to send power to the ECM. When they jumpered the EFI relay, the ECM got power, but then no power was sent to the fuel pump or anywhere else to actually start the truck.

So, obviously, we can't leave everything manually powered or jumpered, but I'm wondering if the next step is to get my hands on a new ECM or something else?? Has anyone else experienced this in the past? If so, do you know what the next best step would be to diagnosing this problem?

Also, if anyone has a used ECM that they don't need, that's fully functional of course, I'll gladly buy it from you. I'm sure they're not cheap from Toyota.

Any help would be greatly appreciated. I need to get this thing fixed this week, so we can take it to the Great Smokies ride in Sparta, TN in May, and I'm out of town till then starting this weekend.

Thanks guys,

Chris

 

[ravencr]

We replaced the ECM and still the same issues. Anybody else experience this on your 80? I'd love some guidance because I'm about to let somebody come pick it up for junk.

 

[Pin_Head]

If it is not the ECM ,then is must be a bad wire somewhere or a bad connector. Start with the fusible links and continue to the ECM. Check for normal battery voltages at the fuse block, but do it with the devices on that circuit turned on so you don't get fooled by an open circuit. If there is a low voltage on an energized circuit, it indicates that there is a bad connection somewhere upstream (toward the battery). An open or unenergized circuit will indicate battery voltage even if there is a bad connection.

 

[ravencr]

That's a foreign language to me. Could you be more descriptive by chance?

Chris

 

[Pin_Head]

No problem.
Turn everything on in the cruiser, including the ignition switch.
Check the voltage at the end of the fusible links away from the battery.
Check the voltages at the fuse block with everything on.
If the voltage is significantly lower than the battery voltage (say less than 10V), there may be a bad connection somewhere between the battery and where you measured the voltage.

 

[ravencr]

So, you think it's just a bad site somewhere even though we have input voltage and no output voltage at the ECM? It doesn't seem to be an issue before the ECM, but I know nothing about electrical stuff.

Chris

 

[Pin_Head]

You seem to have a lot of critical places that have no power, so the first place to look is see if the every circuit in the fuse block is getting getting power. If you find that every cirucit in the fuse block is fine, then you can start looking further away from the battery to the computer. It goes: battery, fusible link, fuse block and then down stream devices like the ECM. Power needs to be flowing in the circuit in order for you to detect bad or high resistance connections using a volt meter. If a connector has high resistance, there will be a voltage drop after the bad connection. Power is voltage x amps. Voltage = amps times resistance.

 

[landtank]

I bought a 96 truck for a grand from a guy who had the dealers 3 top techs spend 3 days trying to get it to start.

I had it running in two hours.

But trouble shooting electrical systems is what I do professionally.

You need to find a guy to take care of this for you. If you can't grasp what pinhead posted earlier I don't think you stand a chance at troubleshooting this one even with our help.

 

[ravencr]

Hey guys,

I don't have the time, nor the expertise, to figure this out. Is there any 80 electrical guys around the Boone, NC area, by chance? Or someone want to buy the truck like it is and get 'er up and running for cheap? I need the truck out of my driveway once and for all.

Chris

 

[Pin_Head]

Are there any diagnostic trouble codes set? If so, this could point you in the right direction. There are extensive trouble shooting guides for engine electrical problems in the FSM keyed to the DTC. Also check DI-110 DI-115 and DI125 sections in the FSM for the troublshooting guides for the ECM and fuel system. You can download a copy of the FSM on line.

 

[ravencr]

No check engine codes that I can tell, but I don't have a reader either. If someone nearby wants to come play with it, I'll gladly donate with some beer and money if it's reasonable. But, at this point, I need to get rid of the truck and move on.

Chris

 

[Pin_Head]

The trouble shooting guides in the FSM for the ECM and Fuel system are very good and easy to accomplish with pictures of what to test and where. I think it is worth a try. Hopefully you can find someone in your area to help. You don't have to be an expert to do the tests in the trouble shooting guide. You just need a volt/ohm meter.

 

[ravencr]

Well, I just don't have time to mess with it anymore, that's the main problem.

Chris

 

[Pin_Head]

Here is an example:

 

[Scamper]

Wish I could help you. I had the exact same problem last year. Dealer had the truck three times (had it towed each time) over the summer, for weeks at a time. At one point they told me it was the ECM, but after replacing it, they found that was not the problem. The basic problem was that the FP was not getting power.

After finally getting the truck back, I found that the diagnostician had left or been fired, but the truck was now working. They didn't charge me for the work. But my greatest frustration was that they couldn't tell me what was finally done to fix it.