Bonehead rookie screwup

[32 Chevy]

Hi, I have been lurking for a while as I have undertaken some personal projects and care for family.

The 32 chevy has been feeling neglected in a cold garage, so to make her feel better on a recent nice day I decided to take her for a drive.... battery dead....

Got the new battery and contorted myself to wrestle it into its hatch buried behind the seats. Hooked it up and got a little flash across the terminals. That should have warned me but no, fasten the terminals...turned the key and the fuel pump screamed in distress! Whoa.... thats not right.... checked the terminals and ya shure, reversed the polarity. Fuel pump,must have been running backwards. *. Now when I turn the key the guages actuate, starter cranks but no fuel pump and CEL light off.

The motor is an early 90's Chevy 4.3 with factory TBI injection, with factory harness. 4 speed manual trans.

Here is what I found so far:

IGN fuse was popped, replaced with new 10 amp fuse. All other fuses are good.
CEL light has 12 volt positive on both terminals.(Key on)  If I jump one terminal to ground light comes on.

I'm afraid I toasted the ECM, but I'm sure appreciative of troubleshooting ideas before sending the ECM to Centech.

[enjenjo]

Do you have any way to read codes? That would be the first step.

[32 Chevy]

Hmmm I think I have one of those old readers in the bottom of the toolbox.... gave a series of beeps. Do you have a tutorial how to decode the beeps, key on / key off etc? Thanks

[kb426]

This web site has a list attached to it.
https://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php

[32 Chevy]

Darn there is an old code reader but its for Ford EFI. The chevy TBI has a rectangular port. I'll ask around....

[32 Chevy]

Jumping A and B with paper clip does not activate any codes ... Turn Key On the CEL light does not light up at all. It light does not come on because there is positive 12 volt power to  ports A and B - no negative. The bulb is good - I disconnected one leg from the bulb, jumped it to negative and the light comes on. The only other wire in the port is red. I followed an online tutorial years ago to strip the harness and naturally cant find it again. Sigh.

[enjenjo]

I have a friend with a pin out connector that amounts to a computer plug that you read the voltages of each pin on the computer to diagnose problems. I have used it in the past to check computers out of the car.

Unless you removed it when stripping wires there should be a high amperage fuse in the system to protect the electronics. On a GM car it is usually in the underhood power center, and kind of looks like a relay but has a clear top.

You might contact Howell engineering  https://howellefi.com/contact/  They have been helpful to me in the past.

[32 Chevy]

Thanks for the suggestions. Problem solved.... I called Howell and talked to their very helpful tech guy named Cory.  It turns out that he recognized the serial numbers on the ECU as coming from them! And sure enough that jogged my memory to the fact that the fella I bought the engine from 10 years ago mentioned something about Howell. Cory said if ancillary systems come on but no CEL or fuel pump, 90% odds the ECu is fried. So, I bought a used one from eBay with same code, plugged it in and whammo, started right up! Yeehaa now I can sleep tonight.

[kb426]

Very good!

[enjenjo]

Thanks for the suggestions. Problem solved.... I called Howell and talked to their very helpful tech guy named Cory.  It turns out that he recognized the serial numbers on the ECU as coming from them! And sure enough that jogged my memory to the fact that the fella I bought the engine from 10 years ago mentioned something about Howell. Cory said if ancillary systems come on but no CEL or fuel pump, 90% odds the ECu is fried. So, I bought a used one from eBay with same code, plugged it in and whammo, started right up! Yeehaa now I can sleep tonight.

Cory knows things he can't talk about. I can't even talk about them myself.