Just purchased a Prius 2003 with 140,000 miles (224,000 Km) P1636 and P3002 keep coming back Aux battery came with car was almost new but after reading some post I replaced the battery with brand new Optima Yellow Top. Hidden menu showing 12.4V~ 12.7V. Car starts and run fine. I am getting around 50 MPG. No issues, car charging battery, goes in stealth mode. No accidents. In January dealer replaced the Airbag harness because the airbag light was on. Please help. Thanks.
what do you mean by READY ? ignition switch at #2 position ? do you want me to check the aux battery voltage in the trunk ?
Two measurements: With the car off (no key in ignition) - measure the 12V battery voltage in the trunk. Voltage: 11.9-12.85V is OK. Less is marginal. Start the car, key in ignition, car started - measure the 12V battery voltage in the trunk. Voltage: 13.8-13.9V is OK. Less is a problem. Bob Wilson
Thakyou for explaining and I appreciate your help. I just checked the voltage : car off = 14.9V engine running = 16.6V Please advice what else I should check.
It looks like the VOM calibration is off. Can you get a cheap, digital VOM? How are you reading the codes? Bob Wilson
My manual does not show a P1636 or a P3002 as a valid fault code for a Gen I Prius. I think you may be using a non Prius aware scanner.
My VOM is digital, you are right it may be showing wrong V, I will get another one. AUX battery is brand new 5 days old Optima Yellow Top 8073-167-51r. I am reading the codes with my OBD2 scanner. What else should I check ? I appreciate your help.
Your OBD2 scanner is not a Prius aware scanner therefore, it is giving you erroneous codes. With the current info we have, unfortunately, we cannot recommend anything else to check. Here's what we know, 1) You're getting some DTC codes (but don't know what they are) 2) Your car runs fine Whatever is causing the DTC's is presumably not causing a problem. Pls do a search on a Prius aware scanner paying special attention to Gen I differences.
I am using my generic OBD2 scanner. I found the following description of the codes : DTC P3002: HV ECU communication malfunction. The traction battery ECU and the hybrid vehicle ECU are not able to pass information; this code is reported by the traction battery ECU. DTC P1636: HV ECU malfunction, reported by the engine ECU. these descriptions are from another post on this site.
Wow, my manual does not show those codes (Haynes). I have not encountered this before. With those faults, I would check the connections on and around the HV ECU. I would probably just unplug and reseat the HV ECU first to see if it somehow got jarred loose. I would also check the connections on the 12V battery to make sure it is supplying reliable, consistent power. I would do that first.
These are impossibly high voltages which means it may be what is going on: Car off - measure battery voltage Turn head lights on - measure battery voltage, should drop to 12.5-12.85 We have not had a report of overvoltage, 12V inverter, but that does not mean impossible. Also, check the VOM calibration against a fresh, battery or other known source. If the car is overcharging, the 12V battery will get hot (not just toasty!) If after a 15-20 minute drive, the top of the 12V battery is warm-to-hot . . . the VOM is accurate and the voltage sense line is bad and/or the 12V inverter circuit in trouble. Bob Wilson
Hi Bob, I appreciate all your help, I will do everything you suggested and will report back. Do you think P1636 & P3002 are not the accurate codes ? I know these dumb obd2 scanners cant read sub-codes but I never had issues reading permanent/primary codes of non prius/hybrid cars. I am new to hybrid world and its my first hybrid so learning everyday new things. Thanks again for all the expert advice. saak
I am not fond of non-Prius scanners because they are really designed to diagnose emissions problems. I've seen them induce false codes and not report all codes. In particular, they don't see the battery or other important controllers. But if that is all you have. If you clear the codes, do they come back? Bob Wilson
I do have a more expensive scanner Autel MD801, but its a generic too. I will try with the other scanner to see if it pick up diferent codes. I have reset the codes multiple times and same codes keep coming back. which scanner should I get ? obviously I cant afford toyota scanner. is there any scanning software available which i can download from the net ? I may have a VAG?obd2 cable which I can connect to my laptop.
One test is to stage from OFF to AUX, AUX to ING, ING to READY, and PARK to "D" checking to see if the code comes back instantly or when the car goes to one of the other modes. Sad to say but I did not check Vol 1 for the follow-up tests for the codes. Vol 1 of the shop manual is pretty through and might help identify where to go next. Bob Wilson
I dont have shop manual. I dont understand "OFF to AUX, AUX to ING, ING to READY" I am new to prius and gen 1 has ignition switch, so if you write to me in novice language would be good. I just connected my Autel MD801 and found more info. I found another code which is Toyota's code C1213: HV System Communication Circuit Malfunction P1636 & P3002 were present too. I appreciate all your help.
Gen 1 is famous for hv battery terminal corrosion. I have seen the corrosion move to the end of the wires that go from the hv battery to the hv battery ecu. I would have a qualified/ confident tech open your hv battery and inspect the connection to the hv ecu. It is possible it just needs a good cleaning. If you find the ev ecu is bad a replacement should be pretty cheap from a junk yard.