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4l60 issues after rebuild

Discussion in 'GM Powertrain' started by, Mar 20, 2010.

  1. New Member

    Thanks in advance for all replies. I have a 1997 k1500 4x4. Factory transmission went out and i bought a rebuilt one from a local transmission shop. It lasted for about 30,000 miles then lost overdrive and drive. I have a friend at a body shop and bought a transmission out of a wrecked 97 pickup and installed, transmission lost overdrive and drive after only a couple hundred miles. It's not my daily driver so I let it set for about a year and decided to rebuild it myself. All went well and after install I had no torque converter clutch lockup. Hooked it up to a scanner and cleared previous codes and tcc started working properly. Put about 600 miles on it and noticed no tcc lockup again and it was slipping especially when shifting from gear to gear. Hooked it up to scanner and am getting p1810 which is transmission fluid pressure switch assembly. I bought a new switch and installed but fixed nothing. If I clear the code the transmission shifts fine until it resets the code. I found that once the p1810 code is set and I unplug my mass air flow sensor the transmission shifts fine and runs noticeably better except for no tcc lockup. I took a mass air flow sensor off a friends truck of the same year and it made no difference. After installing rebuilt transmission i noticed my range sensor also called neutral safety switch was wore out and didn't fit on the transmission shifter properly and my indicator lights were always one gear behind on my dash so I bought a new one. After install truck would not start but indicator lights were all correct. Plugged my old one back in and it still would not start. I ended up bypassing the neutral safety switch by splicing into the wire that sends power down to it from the ignition crank position and running it directly to the starter relay. After all these issues I believe my PCM is at fault but want to be sure before purchasing. Any help or advice is greatly appreciated.
  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Disconnecting the MAF will correct other problems because the computer substitutes known values because of the missing MAF input. Before you condemn the PCM you need to fix the P1810 code. Before you fix the P1810 code you need to correct your splice / hack job and install the correct parts. It's like trying to make Sh** ice cream. No matter what you put in it it still tastes like Sh**. :)
  3. New Member

    Fixed range sensor today and it now starts without my added wire running to the starter relay so i removed that. Cleared all codes and went for a test drive. Transmission shifted and seemed fine except for no tcc lockup. After about ten minutes p1810 was set again and wasn't shifting properly. Put the voltmeter on the red, dark blue, and pink wires, which are supposed to run to my transmission fluid pressure switch, right before the 20 pin connector on the side of the transmission. All read twelve volts. Unhooked the 20 pin connector and hooked voltmeter to corresponding pins and the voltage fluctuated a lot on nearly every pin when I wiggled it. I believe this to be the root of my problems. Can I take apart the connector and repair pins or should I buy a new connector and splice into my wires.
  4. 4wd52

    4wd52 New Member

    Trans issue

    I have a contact at Dana is the owner who is very knowledgeable with these trans. 909-795-1876.:great:
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    You can buy a new internal harness if those pins are loose. The external harness connector would have to be spliced in. The internal harness is known to go bad. Also when testing the Manifold Pressure Switch keep in mind the engine has to be running as oil pressure is required to activate the switches.
  6. New Member

    You seem to be very knowledgeable on this and your input is appreciated. I thought my external connector was bad, but my leads for my voltmeter were too large to fit in the pins, got a different set and it all checks out. I have been following the mitchell diagnostic procedure. Internal harness checks out as well and I have already replaced the old pressure manifold switch. The diagnostic procedure says nothing about having the vehicle running when testing the circuits. Tomorrow I am going to hook up a fused jumper wire to each wire that goes to the pressure manifold switch and ground each circuit while looking at the scan tool. How would you go about diagnosing this problem? Is there anyway this could be caused by something mechanical such as the valve body?? This was my first transmission rebuild and I am sure I could have overlooked something.
  7. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    In a nutshell the computer supplies 12 volts to the 3 wires that go to the pressure switch. When the car is running oil pressure depending on the gear you are in grounds a combination of 1 or more of these wires which tells the computer which gear you are in. Send me a PM with your email and I will send you a PDF which shows the easy way to check this circuit.
  8. New Member

    Well I thought I had it fixed. I sprayed brake cleaner in the connector on the transmission and the blew it dry with compressed air. Hooked it up to the scanner and all was well. Test drove and all was well. Put about a hundred miles on it and I got the same code again. I'm getting close, at least I know where my problem is.
  9. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Good deal. You may want to replace the internal harness.
  10. New Member

    Ended up replacing the PCM because the code just kept coming back and sometimes I wouldn't get any power to the transmission at all and had third gear only. Had the PCM in for three days now without a problem. Well almost, had it in the shop today charging the air conditioner and started to hear this high pitch squeeling noise coming from the motor. It sounded like a bearing running dry or something. The sound started to fade but was replaced by a knock. It wasn't bad at first but it is getting worse... Fix one problem and get another. The pickup does have 220,000 miles but it was running strong. I couldn't believe it just started knocking while it was at idle right in front of me. Anyway any ideas on the likely cause of this? Is there anyway I could get away with a cheap engine rebuild only replacing connecting rods, pistons, bearings and such?

    I have a couple of 350 engine blocks that came out of 88-93 chevy pickups. Can I rebuild one of these and then just take the heads off my 97 and put on the rebuilt engine when finished so that I can continue to drive the pickup
    Last edited: Mar 31, 2010

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