I have a TRAC light on (not TRAC Off) on my 93 LS4 and have detected code of 43. My traction control system and anti-lock brake is not working.

According to my service manual, following are found:
- Code 43: Malfunction in ABS or TRAC control system (I think in this case only TRAC is the problem, not ABS)
- Then the manual goes further and describe as follows:
ABS control system or TRAC control system or communication circuit is abnormal.
Trouble Area: + ABS & TRAC ECU; + Open or short in BRFA circuit.
- Then it goes further and explains how to diagnose the problem and go about fixing but what is explained on the manual is something totally out of my boundary.

Any help would be appreciated.

 

OK. Reading through manuals over and over, it seems that I need to find if the power is going to the TRAC ECU as follows:

1. Remove TRAC ECU with connectors still connected.
2. Measure voltage between terminal BRFA of TRAC ECU and body grounnd. (I am not sure what the voltage I should expected to read? 12 volt?) (What is BRFA?)
3. If the measure is OK, replace TRAC ECU, otherwise check for open and short in harness and connector between ABS & TRAC ECU and TRAC ECU.

I am attaching the scanned page of this.

 

it appears that a scope-meter or oscilloscope would give a clearer pic of this

let me find you a good deal on a suitable model for your Christmas list!

 

I have a scope (actually several), but I know that my wife would love to get a scope-meter for Christmas.
She keeps it well concealed, but I know her pretty well by now.
Looking forward to your recommendation, since the only ones I have personally used are the (somewhat expensive but quite nice - except for the stupid proprietary battery eliminators) Fluke models.

 

I read the service manual over and over again regarding the TRAC code of 43. I was not exactly sure if a scope had to be connected. Well reading through the manual, I did not think a scope was needed and the x-axis is time but there is only pulse action in signal. I can do this with just a simple voltmeter as indicated in the manual I have attached above. I think what it says on the service manual above was to see if the power is going into the TRC relay module if so the TRC must be replaced, otherwise, check for wire harness to see if there is any disconnect or short.

With that in mind, last night I took the TRC down and to see if the power comes to the TRC. I have verified the power does come to TRC. So I took down the TRC and took it apart to see if there is any visual signs of damage. There were no visual signs of damage on the circuit boart but noticed that LScowboy's name was written all over the circuit board.

There are same type of Nichicon capacitors on the TRC board as follows:
1 x 220 microF, 10 volt
3 x 10 microF, 50 volt - (one hidden)
1 x 47 microF, 50 volt
1 x 100 microF, 10 volt - (one hidden)
total of 6 capacitors.

I can try to replace them as I have done it before with the ECM board but there are two capacitors hidden inside a circuit board bracket, which I do not think the bracket is removable.

Now I am stuck again. I need an advise from guru like LScowboy or Yamae. And I am going to ask the forum readers once again. Is there anyone who has TRAC light on with a code 43? Is there anyone who has done a caps replacement on the ABS & TRC board? Any input would be greatly appreciated.

I am attaching few photos of the board for your reference.

 

I don't have enough experience regarding the ABS and Traction control unit for UCF10 and 11 and I can't advise you well.

Are those electrolytic capacitors printed PF(M) or PF(R)?

If so, I recommend you to replace them due to the reason that they contain the liquid "quaternaty ammonium salt" which causes the corrosion badly when aged. But I don't know your problem is fixed replacing them or not.

If I were you, I would check the ripple voltage at the Vcc line of the processor using an oscilloscope first. If the ripples were bigger than 10%p-p of the Vcc, I would replace them in the highest priority. If not, I would follow the service manual and would do the step by step investigations.

 

Thanks for getting back to me, Yamae. I've checked capacitors on the board and learned that it is not Nichicon brand. I think it says KME. Also I check the capacitor markings. I could not read all because of how capacitors are positioned along with other electronic components but I was able to read (M)105 degreeC from 2 caps, which I think means temperature ratings and the question you are asking.

I can change caps but the biggest problem is two of caps that are not accessible because they are under a bracket that cannot be removed. I can change the ones that are accessible but not those two.

The service manual only has two directions. If the voltage ripples are detected then replace the TRC module otherwise check the wiring packets leading to the TRC module.

 

Judging from the top of the capacitor, those capacitors are Nippon Chemicon's because of the mark for the safe valve shaped "Y". They used to manufacture type KME which is the standard and 105 degrees C series. Speaking of the top mark or should I write the shape of the safe valve, Nichicon uses "+" and Rubycon "K". Skilled guys can distinguish them just seeing the top.

Anyway, those capacitors are 20 years old and the internal liquid must be evaporated a lot. It is wise to replace them as a counter measure. The type KME is discontinued and the replacement is KMG but you can select similar type of capacitors seeing the specification available on the Net like this below.
http://www.ndb.com.tw/files/chemi-co...ries%20ECO.pdf

 

Is this going to be same capacitors as the ones you’ve talked about for ECMs? Is capacitors on my TRC the electrolytic, low ESR, capacitors with quaternaty ammonium salt filled-in type? Chemi-con KME(KMG) seems to be a different type. Could I replace capacitors with ones recommended by LScowboy on the ECM thread as follows:
- 1 x 220 mF, 10 volt
o 50V Panasonic FR EEU-FR1H221
o Chemi-con KZE EKZE500ELL221MJ16S
o 50V Panasonic FM EEU-FM1H221
o 50V Nichicon HW UHW1H221MPD
- 3 x 10 mF, 50 volt (M)105degreeC – one hidden
o Chemi-con KZE EKZE500ELL100ME07D
o Chemi-con KZE EKZE500ELL100ME07D
- 1 x 47 mF, 50 volt (M)105 degreeC
o 100V Chemi-con KZE EKZE101ELL470MJC5S
o 100V Panasonic FC EEU-FC2A470
o 63V Panasonic FR EEU-FR1J470B
- 1 x 100 mF, 10 volt – one hidden
o Rubycon ZLH 35ZLH100MEFC6.3X11
o 50V Panasonic FR EEU-FR1H101
o 50V Chemi-Con KZM EKZM500ELL101MHB5D

 

Chemi-con KME was superseded by KMG series, which is a standard high temperature capacitor - not low ESR

 

Thanks for the information. I read through all of your postings, but I am still not sure what capacitors to order as I don't know much about capacitors. Based on what I read, I know it is wrong, but came up with following numbers for Chemi-con brand. Is there different brand I can order if Chemi-con brand is not available? Your input would be appreciated.

Caps I need:
- 1 x 220 mF, 10 volt (Chemi-con KME)
- 3 x 10 mF, 50 volt (M)105degreeC – one hidden (Chemi-con KME)
- 1 x 47 mF, 50 volt (M)105 degreeC (Chemi-con KME)
- 1 x 100 mF, 10 volt – one hidden (Chemi-con KME)

What I think the Chemi-con part number should be:
- 10V, 220 uF -> KMG10VB220M (???)
- 50V, 10UF -> KMG50VB10M (???)
- 50V, 47uF -> KMG50VB47M (???)
- 10V, 100 uF -> KMG10VB100M (???)

For the ECM, LScowboy has done all this for us so all I had to do was call Digi-Key and placed an order with a part number.

 

Those KMG series of Chemi-con capacitors are the best replacements. Other standard 105 degrees C series could be used but I don't know what will happen.

No one has ever tried to analyze and list up electrolytic capacitors for the ABS and TRC unit like LScowboyLS has done greatly for the engine/AT ECU. You will be the first one. He was kind enough trying to help others and I was in a mood to help him some since I have some backgrounds. I can give you some advice as I did for him. My limited English would not be fully OK to explain details. I also don't know the availability of parts there in USA. All I can give you at the moment is as follows.

Try to purchase KMG series of Chemi-con capacitors. If not available, try to find other brands of standard 105 degrees series but stick to Rubycon, Nichicon, Panasonic or major Japanese manufacturer's. Never use others. There are big differences of performances and the life.

 

Actually the problem went away.

Although the capacitor replacement issue still remains. The TRAC code has gone away. I've purchased a used TRC/SRS control module from ebay and replaced the unit. No change in TRAC light or code. I took the unit out again and placed with my old one. Then the TRAC light is gone.

Only conclusion I can come up with is that the connector had some corrosion which caused the TRAC light to come on with the code. I took a electrical cleaner spray and cleaned it out again and put the things back together. Both traction control and antilock brake works fine now.

Lesson learned is that as the car gets older, some of connections on electrical component could cause these types of issues. So before replacing an electric components, check & clean the connectors and see if that resolves the problem.

 

Congratulations on your success to fix. Look at the photo below.
This is the ECU for a JDM Celsior UCF21 engine 1UZ-FE. There exist gold plated pins and non plated pins. The expensive car Celsior even has this type of cost-cuts. The gold plated pins are mostly corrosion free but others are not. Your problem may be caused by {a} non gold plated pin(s).

 

^ i learn so much from yamae! thank you.