Last month the CEL came on. I pulled the code, P2601. That is a coolant pump issue. The common problem is the pump fails. I've been very busy lately, and knowing the car would run fine with this problem, I did not have time to look further until today. My NY inspection is due this month, and I had to make to so the car can be fixed, and pass by the end of the month. Subsequently I realized I was not hearing the pump running anymore. So, today I pulled the CHS W/P relay from the No. 2 relay block (the one on the window cowl in the engine compartment). With a meter, I checked the The voltage on both contact pins (3 & 5) and found 13 volts on one, and nothing on the other. I then checked the resistance on the second contact to ground, and found an open. That meant the either the pump has failed, or there was a wiring failure. I checked the connector on the pump (it is in the drivers side wheel well under the mud shield in front of the tire) it looked ok. I disconnected it (press the tab down and pull off) and checked the pump motor resistance, 3 ohms. That meant a wiring problem (better than the pump, much cheaper to fix). I replaced the connector, and rechecked the resitance to the motor at the relay, and now measured 3 ohms. That meant an intermittant connection. I jumpered the relay contact pins with my ammeter, measured 4 amps of current. Went back to the connector, and flexed the wires. I could see sparks at the junction of one of the wires to the connector. The wire had flexed too many times, and failed. Try as I did, I could not get the connector contact pin to release from the connector, so I pulled off the rubber moisture seal on the back, pulled the insulation off the wire that was left, stripped the broken end of the wire, and soldered the two pieces together. I then potted the back of the connector with silicone. Now the pump works, cost to fixed, $0. Can't do better than that. I'm going to clear the code now, and next weekend get the inspection. Oh, since I have the car jacked up, I will now also change the oil, it has been over 1 year, and 9K miles. The oil still looks clear, like the day I changed it last year.
Thanks for posting this. On my 04 Prius, my CEL came on with P2601 about 8 months ago intermittently and I've just been clearing it out, sometimes daily. It only came on when starting the car or when it cooled off significantly or didn't get really warm. Also noticed that if I heard the pump after shutting the car off at night, I didn't get the code the next morning. Over the last week, no pump sound, and a P2601 every morning. I also have an emissions inspection due by the end on September, and was trying to drive it enough in one day, (after having enough miles to be inspection ready) to be able to pass, and instead decided to take a look at the area you found a problem in. Went to the wheel well in front of my drivers front tire, and pulled the connector, looked fine at first until I noticed the white wire had completed broken where the black plastic sheathing ends. It looks like the hard plastic sheathing was taped too tight(12 years ago in the factory) causing strain on both wires where it leaves the sheathing to go into the connector. The other non-broken blue wire had a hard 45 degree angle in it and was starting to fray from getting scratched by the plastic sheath so I wrapped some electrical tape over it. Had about 1/2" of the white wire to work with outside the connector and plenty on the other side. Stripped the wires and saw that one side was all black with the other mostly black, so did a gentle strip-scrape to make both ends copper-colored and twisted them together really tight. It was right up against the connector at that point so put silicon all around the exposed copper, plugged it in without putting strain on those two wires, tested by turning the car on then off, and wa-la!, heard the wonderful sound of the storage pump again. Cleared the P2601 code for what is hopefully the last time and will get my inspection today or tomorrow. Cost: About $8 for the some silicon. BTW: Original owner at 12 years and 265,000 miles and still using the original heat storage pump, My car was too old for the previous TSB and the heat storage pump was working fine at the time(and still working). I have a second month production 2004, built in the fall of 2003. Here's some pics of the trouble, the last one is my repair:
Follow-up: Cleared the trouble codes and waited a few days of driving for all "Ready" monitors to come on (using the Carista smartphone app), went to get the free Illinois State Emissions check and passed easily, although the guy was shocked that I had 256K miles on the car. Non-thread related: Right after that went to a Toyota Dealer and purchased a 2014 Plug-In Prius/30K miles. At least as I sell the 2004 Prius/265K mile Prius(on my own), I'll know the new owner will be getting a nice, working, well-maintained car that just passed emissions.
Thanks for this. Looking at mine, the plastic piece is broken. Anyone know the name for this? Thanks.
My Prius has P2601on for long time. Today, after reading about CHS W/P relay I checked that relay by exchanging relays between fog light and CHS W/P . After exchange, the fog light can not work as usual but the pump works( it gives noise again) . So it's bad CHS W/P relay . I opened the blue relay cover, used sand paper to clean the two contact points of relay. Then checked with fog light again. This time it works. I think I fixed the p2601 problem. Thanks !
