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HO2 heaters

Tiny
STEVE W.
  • MECHANIC
  • 13,066 POSTS
The pump turns on for 2 seconds at initial key on to prime the system. Then once you start it the PCM turns the pump on once it sees an RPM increase from the engine starting. Once on it stays on until the PCM sees a bad input like no oil pressure. When you shut off the engine it powers the pump off until you restart the engine. From your description it sounds like the pump control wire is the issue, that is what pin 22 does, it grounds the relay to turn it on.
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Saturday, March 20th, 2021 AT 5:07 PM
Tiny
QFONG
  • MEMBER
  • 92 POSTS
Well, I'm not lucky today. I found that when I plug in the PCM and turn on the power, the fuse that feeds pin 57 and 37 blows. I tried two of my spare PCMs and same thing. What I will do is put two headlight bulbs in parallel where the fuse is and start snipping wires until the bulbs go out. But first I'm going to take a couple of days off. What I would really like to do is start over with a new or used PCM connector but can't find one so far. Any ideas?
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Sunday, March 21st, 2021 AT 1:42 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,066 POSTS
You might find an empty shell that has the pins you crimp to your wiring but in new that's about it. You might try car-part. Com and see if you could find an engine bay harness and start with that.
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Sunday, March 21st, 2021 AT 2:19 PM
Tiny
QFONG
  • MEMBER
  • 92 POSTS
After repairing some wiring mistakes and installing a new TSS, the car runs pretty good now. I have all the gears and it idles at a normal 750 RPMs. Also I repaired the harness connector to the PCM as a temporary measure. I have a connector from a 2.0 Mystique and I'm going to drill out the blanked off contacts that are needed for the 2.5 and epoxy in the contact sleeves that are missing. Then I'll have all new pig tails to splice into the harness.
I'm in Florida now and will go back North in a few days and return next December.
Thank you very much for all the help you and your colleagues have given me.
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Monday, March 29th, 2021 AT 12:28 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,066 POSTS
Sounds like you made a lot of progress.
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Monday, March 29th, 2021 AT 2:53 PM
Tiny
QFONG
  • MEMBER
  • 92 POSTS
I've been driving it around the last few days and it runs a lot better but there are still some problems.

1. I still don't have converter lock-up or O D. I drove it to 65 mph, 4,000 RPMs.
2. It stays in 1st and 2nd too long and downshifts way too easily.
3. The shifts are abrupt both upshifting and downshifting. Could that be the Lucas transmission additive?
4. When I started this project, I put a new TSS sensor in and supposedly Rock Auto gave me the correct one for cars built before 1/1/95. I checked the old one today and the resistance is 781 ohms. I haven't been able to check the new one yet.
5. When I was parking the car today, the idle speed had fallen to 500 RPMs and the car stalled twice.
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Tuesday, April 6th, 2021 AT 3:32 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,066 POSTS
Abrupt shifts sounds like internal leakage that suddenly stops, like a bad sealing ring or bushing. It leaks past it, then suddenly it seals properly and shifts. That and the lack of shifting sounds more like a rebuild will be needed as the internals are worn bad enough that not much will help.
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Tuesday, April 6th, 2021 AT 6:59 PM

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