P1637

**Sully K** · 01-27-2020, 07:06 PM

So I took my car (2000 z28)to get inspected and unfortunately it failed. When I brought it home I ran the scanner and that's what it hit me with. P1637- L terminal circuit. I remember scanning it a while ago (few months, it's been sitting) and it had no problems. It drives fine, and the voltage stays constant. Things to note: I did just install some longtubes on it, as well as a full 3in exhaust. Has cats and O2 sensors and all, and I'm not getting any codes from those. Any help would be appreciated

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***SMWS6TA*** · 01-27-2020, 08:24 PM

check the connector on the alternator. there's a single thin wire that talks to the ecm. it can break easy.

**Sully K** · 02-01-2020, 10:51 AM

So update. I finally got some time to take a peek under the car, and from what I can tell the alternator looks fine. The guage shows that it's charging and all, so I'll probably end up going to grab my test kit to check everything. On a side note, I found this connector dangling, and I honestly have no clue what it might go to. Any help would be appreciated

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***SMWS6TA*** · 02-03-2020, 07:13 AM

what side of the bay is that on? hard to tell from pics.

**Sully K** · 02-03-2020, 07:17 AM

Originally Posted by SMWS6TA

what side of the bay is that on? hard to tell from pics.

Driver's side engine bay, its underneath the ABS module, but everywhere I've looked I couldn't find what it hooks up to. I think I might have to do with ABS as I have an ABS inop light

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***SMWS6TA*** · 02-03-2020, 07:19 AM

Most likely that, I think the air pump had only a 2 wire connector. So I don't think it's that and it doesn't look like it's for the O2 sensor harness either.

Why would your ABS be disconnected?

**pajeff02** · 02-05-2020, 08:02 AM

If your P1637 code persists, I would unplug and inspect your connections (both the harness end and alternator terminal) for corrosion or damage. Also take a look to ensure that your engine grounds are in place, free of corrosion and tight. The hidden ground is bolted to the back of the driver side head.

**Sully K** · 03-04-2020, 06:24 AM

Originally Posted by SMWS6TA

Most likely that, I think the air pump had only a 2 wire connector. So I don't think it's that and it doesn't look like it's for the O2 sensor harness either.

Why would your ABS be disconnected?

Sorry about the late replies, I've been a bit busy. I got under the car and looked around, and everything is plugged in, abs, air pump, everything is solid. I talked with one of my friends who does wiring harnesses for these cars (he also tuned it) and hes stumped too. I got the codes fixed as it was some geometry (tune) to do with he headers and exhaust travel. As for the abs, this car was raced and there's some janky stuff with it.

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**Sully K** · 03-04-2020, 06:27 AM

Originally Posted by pajeff02

If your P1637 code persists, I would unplug and inspect your connections (both the harness end and alternator terminal) for corrosion or damage. Also take a look to ensure that your engine grounds are in place, free of corrosion and tight. The hidden ground is bolted to the back of the driver side head.

I checked the connections as well, the alternator L terminal has a single red wire that leads straight to the ecm, so I'm a bit lost with that. All the other connections are ok, but not in the best shape. I'm gonna see about getting a custom wiring harness made when I eventually swap the busted 4l60e out with the t56 I got laying around. Thanks for the help all!

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**Sully K** · 03-04-2020, 06:28 AM

Originally Posted by Sully K

Sorry about the late replies, I've been a bit busy. I got under the car and looked around, and everything is plugged in, abs, air pump, everything is solid. I talked with one of my friends who does wiring harnesses for these cars (he also tuned it) and hes stumped too. I got the codes fixed as it was some geometry (tune) to do with he headers and exhaust travel. As for the abs, this car was raced and there's some janky stuff with it.

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When I said codes, I meant the exhaust codes. Pretty sure the alternator code is still there, but it operates fine and runs/ drives like a dream

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