Poncho0206

Ok this is going to be long winded but I want you all to have all the information I have. I have a 2002 Tacoma automatic Pre-runner. I have had trouble in the past with the temp gauge going up and down. It will be normal one second and then jump to the red the next and back and forth. It done this a few times with me a few months ago but not all the time. It might go a few weeks between doing it. I found a crack in the radiator about a month ago so I replaced the radiator, hoses, and t-stat and fluid. It's been fine for over a month. Yesterday on the way home the temp gauge started going up and down. It never would stay near the red for long. I pulled over and checked my hoses and the weren't tight like the thermostat was stuck. I pulled the cap off and the fluid was full in the radiator as well as in the over flow tank and none boiled out like it was really running hot So I just kept driving it. On the way in to work this morning after about 20 miles it started jumping up and down again. After a few miles it went up to the red and stayed there so I pulled over. Hoses weren't tight. Took the cap off and no boiling out or anything so I drove on. A few more miles and it was still in the red so I was worried about it and pulled over again. I put the truck in reverse and it wouldn't move. Note that I have never had any issues with the trans before. I then put it in drive and it just started jumping and went dead like a manual transmission would do if you were to try to start off in a high gear. I cranked the truck again put it in reverse and it backed up perfect. I put it back in drive and it went dead again. So I started thinking maybe my trans might be over heating and causing my coolant temp to rise so I checked the trans fluid and it wasn't burnt smelling or discolored. The coolant is clear. The engine and trans fluid or perfect looking. I had the truck towed and when I got it unloaded at home I put it in reverse and it worked perfect again. I put it in drive and it was acting fine. I started up the hill by my house and it started jumping again like a manual transmission would if you were in to high a gear but wasn't going dead but it was jumping really bad so I threw it in neutral. I'm lost. I don't have a clue where to start. I'm assuming it's something electrical because it hasn't made and noises or given me any problems before. So I have got an issue with my temp gauge and now my transmission. Any ideas or information would be greatly appreciated!! Thanks Drew

Poncho0206

Anyone?

millball

I'd look to cleaning the battery cables and making sure that all the engine, frame and body groundings are clean and sound.

Poncho0206

Ok I will try that tomorrow. Any idea how man grounds their are? Just to update I changed the temperature switch and sensor this evening. When I cranked it up cold it wouldn't go in reverse. I cut it off and turned it back on and it shifted perfect in forward and reverse. I drove it up the road a few miles and it was shifting perfect but the temp gauge was doing exactly like before. In and out of the red. I had a scan diagnostic tool hooked up to it so I could see what the true temp was. It ranged between 195 up to 203. Stayed around 199 for the majority of the time so maybe my gauge is working. After I drove it back to the shop I popped the radiator cap off and just a small amount of fluid came out but still no boiling. While it was still hot I pulled the t-stat out to confirm it was opening and it was opened a little. I see movement when it is running in the radiator but I wonder if I'm just not getting enough flow. Do you guys think I need to replace the water pump? Is their any way to test if I am getting enough flow? I really think I have got to have some sort of electrical issue with the tranny acting up because of it working properly most of the time and I have never had an issue with it before today. I think I'm going to go ahead and put another new t-stat in it and try leaving the coolant below the neck so I can try to see the flow through the radiator better. Let me know your thought please! Thanks!!