TCS / Slip / ABS Relay . . . ? - SOLVED

[jbreckeen]

Hello all.

I am diagnosing a problem in my girlfriend's car - a '97 Q45t. Yesterday the TCS off, Slip, and Check Engine lights came on, and the car has almost no power.

So, full disclosure - I am a lifelong German car man and have been wrenching on them for many years. But I have not done any work on Eastern cars - ever. I have used the search function of this fantastic site, and have come up with the ABS relay problem. I do like the fact that this part will have a small cost, but my question is would this problem affect the acceleration? Is this some sort of limp-home mode? Does this car have a limp-home mode?

To elaborate: the above lights come on once the engine is started without even moving. The car starts and idles perfectly, but as soon as you press the accel pedal, the engine just chokes all power - though it will not stall. If you are very soft on the accel pedal, it can accellerate and drive, but without almost any power. There are no abnormal noises coming from the car or abs actuator - except when you try and rev the engine, it just sounds like someone is choking it.

I have seen the FSM's on this site - thanks much - but I cannot work on it until this weekend, when I will pull the codes. So I am asking the collective wisdom here is this makes sense. In my German experience, it seems like the throttle-position sensor would be faulty, but I will check both.

Thanks in advance guys . . .

JBreckeen
St. Petersburg, FL
1997 Q45t

[loystock]

Welcome to NICO.

From my experience, a defective ABS relay will cause the lights to turn on but not affect the engine power. So better have an OBD II scan to isolate the problem. Also, a failing alternator can cause all sorts of problems. So make sure your battery connections are clean and tight and that battery voltage is >12,5 VDC (a weak battery imposes a heavier load on the alternator). With the engine running, check the alternator charging voltage to the battery is >13.8VDC and steady (spec is 14.1-14.7 VDC). Rev the engine to @ 1500 RPM and check voltage remains steady.

Assuming the alternator is OK, the accel issue may be due a failing TPS though a defective Knock Sensor can also cause lousy acceleration (due to ignition retard).

Since you have access to the FSM, there is a diagnostic procedure for the ABS/TCS/SLIP light and all you need is a jumper to Pin 9 of data link connector and chassis ground. The procedure will also tell you how to interpret the test result and correlate to a symptom chart.

Again, check your alternator first before going further with the diagnostic..

[jbreckeen]

So, thanks for the advice.

I first pulled the codes to the TCS brain, and it gave me "Engine Component Fail". So I pulled the codes from the ECM, and it gave me the code for the MAF, Front O2 sensor, and both knock sensors!

I found a fairly priced MAF from Ebay, installed it today - and tah-dah, all is well in the world again.

I will look into the O2 sensor, but from what I have read it is a PITA to get too - I thought this car was large . . . well, I guess since they had the space, they decided to install 5 million O2 sensors!

Anyway, thanks again . . .

JBreckeen.