Repair
Gen 1 Prius Steering Rack Failure, Code C1513 Torque Sensor Malfunction
(This blog is one in a series on Gen 1 Prius common failures. Read the introductory blog here.)
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Classic Prius, model years 2001, 2002, and 2003, employ a 12V electric motor for power steering assist. The following is an explanation of how the system is designed, how it fails, and how much it costs to fix.
The motor is integrated around the shaft of the pinion gear (input part of the steering rack) and the amount of assist is interpreted through a torque sensor, mounted at the top of the motor. The sensor has two pads, each with two “fingers” (think of the needle on a record player); as the steering wheel is turned the sensor flexes, changing where the fingers touch the pads, which corresponds to varying voltage values sent to the steering computer. The amount of flex translates the resistance to steering and, therefore, the amount of assist needed.
This sensor has a penchant for failure, triggering the “Problem” screen on the center display, illuminating “PS MAIN” for power steering (pic forthcoming), and setting trouble code C1513: Torque Sensor Abnormal/Malfunction. Out of range voltage values are saved in the computer’s “freeze frame” at the time of failure and confirm the code and that the sensor is bad. The component cannot be purchased separate from the rack.
Other symptoms include jerky steering assist (sometimes quite frightening). It’s possible for the code to set with no change to steering performance.
We have also experienced intermittent steering assist from cars with no codes or warning lights (but no less scary), which may originate from the torque sensor or internal failure of the assist motor windings. Regardless the rack must be replaced as a unit.
Toyota did issue a recall campaign for steering racks on early models (first three months of the 2001 model year run, produced between May 9th, 2000 and July 21st, 2000, which equates to less than 2000 units), with replacement covered by Toyota for free.
PDF of Toyota Special Service Campaign Y05, 2001 Model Year Prius Power Steering Gear, Letter to Dealers
(an interesting look at Toyota’s attitude towards Prius early adopters)
Of the cars we’ve seen with rack failures, none was produced during this small window (which makes you wonder what exactly they improved); in fact we’ve even seen a failure in a car that already had its rack replaced under this campaign (years ago). In short, while there is a chance your rack could qualify for free replacement, it’s not likely. We do however check to see if the campaign applies to any vehicle’s we diagnose with this condition.
Given the widespread failure of these components, we no longer entertain used replacements. We did replace a rack with a used one once, at the owner’s insistence, and it ended up being bad “out of the box” and proved a real PITA for everyone involved.
The good news is that new racks are readily available from dealer parts departments and can be replaced quickly and easily. The unit is mounted to the top of the vehicle subframe (on John’s hand, in pic); there are a few tricks to stay out of trouble (a cautionary note to other techs who may be reading), but LG charges 2.5 hours for R&R plus a front wheel alignment.
Prices
Price breakdown for the job:
Labor: $300
New Steering Rack: $1499
Front End Alignment: $85
Sales Tax: $142.41
Total: $2026.41
Posted by Carolyn
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Prius Tires
The Prius doesn’t need much, but it does go through tires. The first generation—a small, heavy car thanks to its hybrid components—calls for Bridgestone Potenzas, which can be safely inflated to 50psi to maximize fuel economy and tread wear. After learning the hard way, many owners attest to getting the most for their money both in tires and gasoline with this product.
The second generation Prius comes stock with a different, more standard-sized tire, the Goodyear Integrity P185/65R15 86S, which lasts 40,000 miles at best (consistent inflation to 40psi and rotations every 5000 miles) and less than 30,000 miles at worst. It’s designed to get optimal fuel economy results for EPA certification (numbers listed on the label when the car is for sale), the top priority for Prius buyers, and therefore compromises on other performance specs such as endurance and traction. Given their short lifespan, Gen 2 Prius owners have been quickly posed with the question of tire replacement and how to improve on the original.
Being specialists, we have been vetting the plethora of choices for some time (OMG PriusChat) and have currently settled on the Goodyear Assurance FuelMax, in the standard size of 185/65R15 86T (slightly higher speed rating than original). I like this tire because it keeps with the OE brand of Goodyear; it’s specially designed to maximize fuel economy while tipping its hat to the most common complaints of poor traction and short tire life, all at a reasonable price.
LG does not maintain its own tire equipment, for lack of space and, frankly, lack of profit (tires are a highly competitive market and they don’t require our technical expertise to change). That said, we do advocate for informed, responsible tire choices and therefore carry the Potenza and Assurance FuelMax in stock (Potenzas are also the best for the Insight, and we carry that size too). Because the market is often slow to respond to hybrid trends, the correct tires are occasionally on backorder—problematic when you need tires now for a multiyear, high-dollar investment.
We purchase through Tire Rack at wholesale prices and mark them up to compensate for our expertise and the convenience of having them in stock. Individuals can also purchase from Tire Rack directly at a slight cost savings.
We sublet tire mount and balance to Larkins Brothers Tire a little over a mile away; they’re as green as any regular shop (which is to say, no greener than what’s required by law) but they’re honest, inexpensive, fast, and their employees seem well treated. (We also use Robert’s Tire around the corner when we’re in a rush, they’re a little more expensive and not quite as fast, but proximity allows us to leave the car and walk back to work and they’re equally capable and honest.) We do not mark up for installation ($25 per tire) but are willing to facilitate the service as a courtesy of getting it done while your car is already with us and not having to deal with a separate service facility.
All told, the cost of a tire, installed, is as follows:
Gen 1 Prius (model year 2001, 2002, 2003):
Bridgestone Potenza P175/65R14 RE92 XL - $108.80
9.5% Sales Tax - $10.34
Mount/Balance/Fees - $25
Total - $144.14/tire
Gen 2 Prius (model years 2004, 2005, 2006, 2007, 2008, and 2009 with the standard package)
Goodyear Assurance FuelMax P185/65R15 86T - $106.53
9.5% Sales Tax - $10.12
Mount/Balance/Fees - $25
Total - $141.65/tire
Gen 1 Insight (model years 2000, 2001, 2002, 2003, 2004, 2005, 2006)
Bridgestone Potenza P165/65R14 78S - $111.80
9.5% Sales Tax - $10.62
Mount/Balance/Fees - $25
Total - $147.42/tire
Tires are critical to safety: evidence pics from a 2006 Prius tire that literally wore through the steel belts and blew on the San Francisco Bay Bridge last Saturday. Many people swear by Costco; just yesterday a customer was telling me how he got 90,000 mile Michelins that originally lost on fuel economy (a common complaint with Costco tires) but is now getting 2 mpg better than original (which he and the salesman attributed to the treads “firming up") for $400 out the door (though he suggested this was a special sale price). Other popular choices are Yokohamas and Kumhos. Just last week I put a customer into Nexans because his car was a city workhorse and he didn’t mind current vehicle traction.
Obviously tires are high consumers of natural resources and the lifespan of the tire entails its own built-in fuel economy. Traction is another serious concern, in terms of safety and the resources entailed in repair and tow after an accident. The second generation Prius remains fairly new, and few have gone through enough tires to really know how long the replacements will last and what the lifetime fuel economy and other performance specs are. At some point the question is a Buridan’s ass, and there are as many tires available as there are advocates for buying them.
For more information on tire choices in the paradigm of fuel economy, check out:
Tire Rolling Resistance, Part 1 via TireRack.com
Tire Rolling Resistance, Part 2 via TireRack.com
Tire Rolling Resistance, Part 3 via TireRack.com
Posted by Carolyn
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Gen 2 Prius Leaking Water Pump
Second generation Prius have four water pumps, three electric and one mechanical. The mechanical pump is much like those on conventional four-cylinder engines: it is belt driven and bolted on with a handful of 10mm fasteners. Like regular cars, it also has the potential to leak. Initial signs are a pink crust under the weep hole; coolant residue eventually spreads around the shaft seal and down the front of the engine. We’ve never seen them bad enough to cause enough coolant loss to overheat the engine but there’s no question that the pump should be replaced. The good news is that the repair is straightforward and reasonably priced. Book time is just short of two hours, we charge an hour and a half.
Engine Mechanical Water Pump = $103.89
Toyota P/N 16100-29156-83
1.5 Gallons Super Long Life Coolant = $30.00
Sales Tax = $11.38
Labor = $180
Total = $325.27
Posted by Carolyn
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Prius Code P0A93: Inverter Water Pump Failure
All hybrids have “inverters"—assemblies that translate high voltage direct current (DC) of the battery into alternating current (AC) for the motor/generator(s) and into low voltage DC to charge the accessory (12v) batttery. The chopping and reconstituting of current creates heat, which must be dissipated for the components to last. Honda hybrids are relatively light duty and can get by cooling the inverter with air, tucking it back near the trunk alongside the battery. Toyota “hybrid synergy drive” style hybrids are heavier duty and require water-cooled inverters, which is why they are located under the hood (for proximity to the radiator).
On the water-cooled varieties, the “inverter water pump” circulates the coolant from the inverter to the radiator whenever the car is on. Circulation is confirmed by removing the cap on the inverter coolant reservoir and checking for turbulence (see video below). If turbulence is missing, one of the following is true:
1.) The inverter water pump has failed
2.) The pump circuit is open (no power e.g.)
3.) The cooling system is blocked (kinked hose, e.g.)
4.) The cooling system has an air pocket
Regardless of the reason, the lack of circulation will cause the inverter to overheat, setting a trouble code. On the second generation Prius (model year 2004-2009) that code is P0A93, information subcode 346: “Inverter Cooling System Performance.” Diagnosis commonly leads to a seized water pump, a problem we’ve seen multiple times on Prius as young as 55,000 miles.
Toyota has updated the design of the replacement pump (part number G9020-47031) to solve the problem. You can tell the updated design from the original by the color of the mounting base (black is original, silver is updated) though late models with the updated design (silver base) have also experienced failures. Toyota has also issued a Technical Service Bulletin outlining the failure on 2004, 2005, and 2006 Prius: TSB EG001-07.
The pump can be replaced from above in just over an hour (LG bills 75 minutes), with a cost breakdown as follows:
Toyota Inverter Water Pump G9020-47031 = $138.86
Quart of Super Long Life Coolant = $5
Sales Tax = $13.67
1.25 Hours Labor = $150
Total = $307.53
Posted by Carolyn
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LG TV - Prius Dead Dashboard
The latest fad in Prius failures is the dead instrument cluster (combination meter): we have repaired two and since heard of others across the country. Our first hand patients happened to both be cabs (both 2007 models, with 119k and 156k miles, see video below); a little digging on ye ol’ Internet revealed another cab with this problem (2006 model year with 182k mi) via PriusChat. My salvage contact (Steve at AutoBeYours.com) also reported cluster failures from a cab company that buys from him.
A case posted on my beloved iATN (link for iATN members) came from a dealer tech in Cordova, TN, on a 2008 with less than 15,000 miles (effectively brand new) which he eventually attributed to cold temperatures. We have several customers with high mileage, second-generation Prius with no such problems (e.g. our favorite Prius, see blog) and know of lots of similarly trouble-free Prius in much colder places than Tennessee. There’s speculation about coffee (or other liquid popular with cabbies) getting spilled on the dash—the plateau before the instrument display makes a nice shelf for such things—that may be the missing link and a likely secret. For now the root cause remains unknown.
The primary symptom is a dark instrument display, center speedo/combo as well as peripheral indicators (including “ready” light), with the exception of the “check engine” light, turn signal indicators, and security light (explanation of this to follow). The cluster may go down while driving or at initial start-up. Sometimes the condition coincides with a batch of interesting behaviors: the reverse lights, power button, and rear hatch release are inoperative. This is especially disturbing since it makes it challenging to turn the car off.
The solution is replacing the combo meter/cluster. Extricate the top dash panel, flip it over, and remove the white plastic cover to expose the speedo circuit board. New ones are available from the dealer for a mere $711 (special order) and can be programmed with the original mileage. With ninety minutes labor, the total bill is $951. The other option is a used board; while cheaper ($250-ish) they cannot be reprogrammed and will read the mileage of the host vehicle. If this is less than your car, it could be a bonus. If not, not. Total bill with labor, $451.
That said, what’s the explanation for the weird behaviors? It’s mostly confusion over vehicle speed: the speedo acts as a gateway to broadcast related information to other “body” ECUs on a dedicated communication bus called BEAN (Body Electrical Area Network) including those in charge of the power switch and the rear hatch. If the vehicle is moving (or it can’t tell), the Power Source Control ECU interprets brief presses of the power switch as accidental and ignores the request, a safety feature to keep you from inadvertently shutting down the car when moving. If the power button is held down, the car interprets it as an emergency and shuts down no matter what speed. This function still works even when the instrument cluster goes down. 
Likewise, the vehicle will prohibit the hatch from opening if it doesn’t know what speed its going. Reverse lights are not related to speed, simply controlled through the combo meter according to gear inputs from the HV ECU.
The “check engine” light, turn signals, and security lights continue to work because their circuits are independent of the main computer processor inside the assembly (see wiring diagram, pictured).
Video of our second troubled cab, before the Power Switch stopped working:
Video of the same cab when the Power Switch finally acted up:
Video of case posted on PriusChat: