TubaTwo

Last week, my xB experienced a major loss of power, rough idle, and warning lights on the dash, including CEL. It was just like my previous experience before having ignition coils replaced just the week before.

Anyway, the dealership tells me the main engine wire harness needs to be replaced. I'm off warranty and it will cost over 1K. Needless to say, I'm not too happy since this doesn't seem like a problem for a car with less than 50K miles and 4 years old.

I asked the service manager for copies of the relevant TSBs and read through past posts here and some other sites. It seems to me that the coil problem typically happens in hot temperatures. Both times I had a failure our high temps. were below 70F. It seems to me that the wire harness was actually causing my coil failure. Am I on the right track here?

Invertalon

What is with this car and harness issues?

I never had the rough idle or loss of power issue, but I did have the Trac/ESC/ABS lights come up. Found out here that it was the ABS harness. I took off the speed sensor clips on the rear wheels, cleaned them, applied dielectric grease and put them back... Lights never came back.

I had the ignition coil recall done and right after my airbag light was on. I took it RIGHT back, knowing it was due to whatever they did. I had to pay $50 for them to tell me my airbag harness was shot and needed to spend $1500 to replace it. HA! They reset the battery and it never came back... Wish I did that first... Would of not been out $50!

And I hear of the issue you have right now... Try resetting the battery and clearing the codes. See if it gets rid of your issue!

TubaTwo

I haven't had the ABS light, but both times I had the ignition coil replaced and this time with the main engine wire harness I get Trac, ESC, and CEL.

ScionFred

iTrader: (1)

No. The harness is not causing coil failures. The problem with the harness is that it can cause random CELs to appear. Very likely a shielding issue. The easiest fix is to remove your negative battery cable for a few minutes to clear the CEL. A better option is to invest ~$100 in a OBDII scantool so you can read the CEL codes and reset them yourself. I too have an early 08 XB with the "faulty" wiring harness and it's never been a problem. How often does your CEL come on?

TubaTwo

It has only come on 3 times in the four years I've owned the car, but the first two times my dealer replaced engine coils.

So, if the wire harness is truly a separate issue from the engine coils, why did it feel the same (extremely rough idle and big power decrease) and look the same (CEL, trac, and ESC) for both issues? Was the wire harness just creating codes that led the dealership to believe the coils needed replacing the previous times?

TrevorS

iTrader: (1)

Yes, that seems to be the explanation! My 2008 is post the harness cutoff and I've exerienced coil problems. My solution was to replace the specific coil and it's been fine since, but there's a coil replacement service campaign in progress ! My interpretation is the harness issues imply coil problems, but they aren't actually born out. However, that doesn't mean the early harness isn't itself a problem !

ScionFred

iTrader: (1)

It's impossible to say what was wrong without knowing the OBDII codes that were present. That's why I highly recommend getting a scantool or at least having the codes read at Autozone, etc. Whenever the ECU sets an active DiagnosticTroubleCode the CEL, trac and VSC lights come on. For example, I installed a racing thermostat and got the same warning lights because the engine coolant temp was lower than expected. The car ran great but the CEL lights stayed on. The harness can cause false codes but I don't think that is the case here. If the harness were a problem you'd have codes present but the car would still run fine.

In your case it's possible that you had a bad coil which the dealer replaced with similarly defective coils, one or more of which failed again. My understanding is that there was a defect in the coils which often led to premature heat-related failure. At some point the coils were re-designed to eliminate this defect but I'm not sure of the timeline.

For your immediate engine trouble you need to know what codes are active in the ECU. Modern OBDII ECUs are very good at pinpointing exactly what is wrong. If you could get the harness replaced for free under warranty I wouldn't recommend against it but I highly doubt that it is the harness that is causing your engine to run poorly.

TubaTwo

That was what I was worried about. I was originally quoted $1,200 for the wire harness repair. I've managed to negotiate the price down by talking to Scion Customer Care and the dealership's service manager. I'm afraid, though, that if I get the harness repaired, I will still be having other problems with the rough idle and loss of power. I don't want to be stuck with multiple repair bills on a car this new (4 years, 38,000 miles).

ScionFred

iTrader: (1)

Is the dealer claiming that the only thing wrong with your car is the harness? It is possible that the harness may have become damaged over time due to improper installation, etc. That would be separate from the TSB issue which consisted of causing certain false CELs to appear. I get an occasional P0101 for MAF performance but it has never affected anything so I simply reset it. To me that it far preferable to letting the dealer replace my main wiring harness.

I still strongly suspect that the cause of the rough idle and loss of power is something other than the harness and that the dealer plans to replace more than just the harness. I could be wrong though. Ask the service rep what codes are active. That will tell you what's really wrong. Good luck.

TrevorS

iTrader: (1)

No affront intended, but this has the scent of conspiracy theory ! Still, just because we're paranoid doesn't mean someone isn't out to get us. To be sure, what you're saying is possible, but to dummies like me, it seems less than probable ! In any case, I'm inclined to think the earlier harness may be inclined to cause misbehavior.

I suspect most coil replacement is a result of misunderstanding of the reported problem. As much as we'd prefer it to be, this stuff isn't cut-and-dry ! Still, only insider info can tell for sure.

ScionFred

iTrader: (1)

No affront taken and when it comes to scumbag, rip-off, soul-less, destined-to-rot-in-hell-for-eternity dealer service departments, I usually do expect the worst and am seldom disappointed. There is no DTC for a bad wiring harness so the ECU is telling them that something else is wrong. The SD is interpreting that data to mean that the harness is bad. The most credit that I will give them is that they might be honestly wrong/incompetent rather than intentionally lying about it to rip off the customer.

I've had the defective wiring harness on my car for over 5 years and 56k miles now and the worst problem it has caused is an occasional P0101 DTC that has zero effect on engine performance. I simply reset it and it goes away for at least 5k miles.

S-SB-0050-08
November 12, 2008
M.I.L. "ON" DTC P0101, P0172, P035 #, P2237 or P2238
Service Category
Engine/Hybrid System

Section
Engine Control

Market
USA


Applicability
Introduction
Some 2008 - 2009 model year xB vehicles may exhibit a M.I.L. "ON" with one of the following Diagnostic Trouble Codes (DTCs):
^P0101 - Mass Air Flow Circuit Range / Performance Issue
^P0172 - System Too Rich
^P035 # - Ignition Coil '# ' Primary / Secondary Circuit
^P2237 - Oxygen (A/F) Sensor Pumping Current Circuit / Open
^P2238 - Oxygen (A/F) Sensor Pumping Current Circuit Low

An improved engine wire harness has been developed and implemented in production to address this condition. Use the following repair procedure to diagnose and repair customer complaint vehicles.
Production Change Information

This TSB applies to vehicles produced BEFORE the Production Change Effective VINs shown.

Parts Information

Warranty Information
APPLICABLE WARRANTY
^This repair is covered under the Toyota Comprehensive Warranty. This warranty is in effect for 36 months or 36,000 miles, whichever occurs first, from the vehicle's in-service date.
^Warranty application is limited to correction of a problem based upon a customer's specific complaint.


Required Tools & Equipment
Additional TIS Techstream units may be ordered by calling Approved Dealer Equipment (ADE).
Repair Procedure
1.Using TIS Techstream check for stored DTCs.
2.Verify one of the following DTCs is present.
^P0101
^P0172
^P035 #
^P2237
^P2238
NOTE If other DTCs are present along with any of the DTCs listed above, this TSB does NOT apply. Follow Repair Manual procedures to diagnose those DTCs.

3.Follow Repair Manual procedure to inspect the DTC-related component(s).


Refer to the Technical Information System (TIS) applicable model year Scion xB Repair Manual:
4.If the DTC-related component(s) is within Repair Manual specifications replace the engine wire harness.
5.After replacing the engine harness clear DTCs and verify that no DTCs reset. Then warm vehicle to operating temperature and test drive to verify repair.

TSB # S-SB-0050-08 November 12, 2008

This TSB applies to vehicles produced BEFORE the Production Change Effective VINs shown below.

AUTOMATIC TRANS VIN# JTLKE50E*91067111
MANUAL TRANS VIN# JTLKE50E*91067112

TubaTwo

A friend told me that he thought the car's computer compensates for any codes it generates, so a false code for an ignition coil would result in similar symptoms to those I would have if it were truly an ignition coil problem. Is that true, or a bunch of hooey?

When I had ignition coil problems (according to the dealer) previously, I'd have an extremely rough idle and a big decrease in overall power when driving. That is also what I am experiencing now. Are those the usual symptoms of a bad ignition coil?

As far as my current problems, I've e-mailed the service manager again to ask which codes were present when they made the diagnosis and asked why I am experiencing the rough idle and power decrease if the wire harness issue is creating false codes.

ScionFred

iTrader: (1)

Your friend is partially correct. Under certain circumstances the ECU can enter into safe mode to protect the engine. However a stored code for a faulty ignition coil would not cause any effects of a bad coil.

As far as what is causing your current problems, it could be several things including a bad coil but since the ECU already has the answer stored, I'd rather not guess.

TrevorS

iTrader: (1)

As Fred pointed out, the best defense is to get yourself an OBDII code scanner (or at least beeline to the nearest Autozone and get the codes read). I purchased mine for about $60 via Ebay -- very satisfied !

r2d2michael

well...crap. i get the p0101 and get the p2238 and p2237 codes.... every month or so. i just clear them with my scan tool. but i have a 2009 so i thought it was made after it was fixed.

TubaTwo

I got a scanner and my active codes are P0172 and P0101. Do you think this is just the wire harness problem, or do I have something else going on? Also, should I reset the codes and see what happens?

ScionFred

iTrader: (1)

If your engine is running 100% then the codes are erroneous and possibly caused by a harness or some other issue. If the engine is running less than 100% the codes indicate a problem with your mass airflow sensor. P0172 means the engine is running rich and P0101 means that the MAS is not performing as expected. The best advice I can offer right now is to get a can of MAS cleaner at any auto parts store, remove your MAS and clean it. You can reset the codes or leave them as they make no difference in how the engine performs. If cleaning the MAS solves the problem, the codes will reset themselves after a few days or weeks. In the worst case you may need a new MAS. I still seriously doubt that the harness is the root cause of your problems. Good luck.