Code 51 Help
 

Still battling this rebuild. I am getting a code 51 I think it's my ecu. Does anybody have a diagram to test ecu 1988 4x4 truck 3.0 5 speed. I don't even have voltage at the b+ terminal on the test connector. I'm jumping voltage off the + side of the coil to get this signal. Thanks

check your EFI fuse, the EFI main relay and the AM2 fuse
the B+ terminal should be hot at all times

What are the locations of the EFI and AM@ fuse. I've checked every fuse I can locate. Thanks

the efi fuse is under the dashboard in the panel there
the AM2 fuse and EFI relay are under the hood
(at least I think the relay's under there)

Thanks

Besides the code, what problem are you having exactly? Do you have another thread happening that talks about it?

Code 51 doesn't point to the ECU. I mean it could, but that's really last on the list. The idle contacts on the TPS or the A/C circuit would be first to look at.

As stated earlier. I'm having to jump power to the b+ connector in the code test connector just to get the code,fire to the plugs and fuel pump. I'm going to check my ac wires right now to make sure they are hooked up. Thanks I will keep checking back to see if ya'll have any more ideas and if I get this solved I will post the fix.

So, you can't pull the code the normal way by jumping the TE1 and E1 terminals, right?

Thats right. It will try to run as long as I pat the accelerator. But it never raelly catch's and coughs miss fires. Thanks

When you turn the key on to ignition....without starting it......will the CEL come on? Not necessarily flash a code, but atleast come on?

Yes as long as I have the b+ terminal jumped to the + sie of the coil.

Okay.....thanks.

Have you checked to see if power is getting to the ECM at the ECM connector?

I'm thinking it is the ECM, but hate to jump to conclusions on that. What's weird is that you can get power to the coil with the key which means the ignition switch is a working (plus that is will run), but you can't get the diagnostic mode.

Yeah....I think it's your ECM.

Yes with the ignition on.

If you're getting power to the ECM with the key on, then the CEL should come on....normally. Means the fuses, fusible link, relays, ignition circuit, etc. are all working. I think your problem...again.....is the ECM.

One more thing.........

When you turn the key on, do you hear three clicks on the pass side near the dash?

I'll have to check that

I hear 1 click in the drivers kick panel and 1 on the passanger side under glove box. Thanks

Okay.....check the main relay, then. You should hear the main relay power up, the opening circuit (fuel pump), and the ECU. The CEL not coming on with the key alone means the ECU is not powering up. Which makes me rethink it may be the relay.

Okay sounds good. I will check it. I will post what I find. Thanks Again