bguild

Guys,

93 GS300. Trac light comes on after starting car, and hearing about 10 pulses which kind of sound like a pump trying to turn on, but not able to pressurize. Kind of a mechanical sound. Also, when I have the car running, and try to bleed the valve on top of the pump, I get no fluid coming out (not sure if this is normal)

Pulled the codes. 43, 54. So far, replaced the pressure hose and orings, (1) pressure hose: 90947-06009, list $68.75, net $57.29 (4) oring: 90301-13011, list $5.93, net $5.93

and removed the whole assembly just to get familiar with process and check things out. See attached pic.

Since the previous owner already replaced the ABS and TRAC ECU, I am left with troubleshooting and potentially replacing the actuator, accumulator, or pump. I'd like to know what you guys think is the likelyhood of the suspect issue, given your experience with these cars.

Here is a bunch of other information I have collected:


47980-30010 pump
47970-30010 accumulator

43 - malfunction in ABS or TRAC (BRAKE) control system

1) Remove TRAC ECU with connectors still connected
2) Turn ignition switch ON
3) Check voltage between BRFA of TRAC ECU and body ground. If voltage is about 6V (24ms pulse) check and replace TRAC ECU
4) Else, disconnect TRAC ECU connector
5) Now, measure voltage between BRFA of TRAC ECU connector and body ground. HINT: Measure voltage within 8 seconds from the time TRAC ECU connector is disconnected.
6) See step 3 above
7) Else, check for open and short in harness and connector between ABS and TRAC ECU and TRAC ECU. If yes, repair or replace harness or connector
8) Else, check and replace ABS and TRAC ECU

54 - excessive operation of TRAC pump motor

1) Remove ABS and TRAC ECU with connectors still connected
2) Run engine for 30 seconds at idle speed to raise the pressure of the TRAC actuator to a high level
3) Stop the engine and then turn ignition switch ON
4) Measure voltage between terminals PR and E2 of ABS and TRAC ECU connector
5) If voltage is 4-8v for more than 24 seconds, replace ABS/TRAC ECU
6) Else, check for fluid leakage, repair, and add fluid
7) Else, replace TRAC accumulator
8) Else, replace TRAC actuator

jmax.garage

iTrader: (2)

funny, my car doesen't have trac and is missing the button and the light althogheter from the dash.

bguild

one question in particular would be the following:

Are the following part #'s

47980-30010 pump
47970-30010 accumulator

Similar for any other Lexus or Toyota models? For example, are the parts from a 93-97 LS or SC3/400 compatible with the GS300 trac control?

Thanks,

Brian

bguild

another question would be:

Based on my description of "no pressure when bleeding from the valve on top of the pump", can you determine if the problem is the pump, or the actuator, or both?

Thanks,

Brian

jmax.garage

iTrader: (2)

BGBUILD: maybe the n/a AUTOMATIC (no 5 speed) supra parts... let me confirm this tomorrow

bguild

kidzik007, thanks for the replies. This has been a big problem for others in the past, from what I can tell by searching the forum. Anyone else out there who had the problem, and fixed it?

Brian

bguild

thought I would renew this thread, because I have a bit more info.

When I start the car I feel approximately 10 pulses which are perhaps 1 minute apart in frequency. You can sort of feel them through the steering wheel. Because of this, I assume its the TRAC pump trying to turn on, or pressurize. After, the 10 pulses, TRAC light illuminates steady, with consistancy. Seems to happen more quickly on wet/humid days, but takes longer, and sometimes never comes on, on dry/non-humid days.

Is the computer trying to turn on the pump, and failing?

Can someone in the know explain how the TRAC system goes through a test cycle?

Just as a test, the other day, I entered a puddle after starting the car, and tried to spin the wheels. I did this prior to the TRAC light coming on steady. The car appears to engage the TRAC system (flashing TRAC light), and cuts the engine when I do this, but you have to do it almost immediately, before the TRAC light comes on steady after what I think is the failed test cycle.

If anyone has any more info, I would really appreciate it.

Thanks,

Brian

Paul_Cos

Got the same problem....have tried just about everything. For now, have just disconnected the TCU to avoid the light, etc. Now of course I have no traction control. Anyone figure out what the problem is?

sasakura

Having similiar problem on my '94 with 100K but there doesn't appear to much tech help on this forum.

BKzSC400

weird? i see trac light on my cluster but no switch on shifter? how come?

jmax.garage

iTrader: (2)

check the pulleys... hmmmm.... what about a brake flush? air in the ABS? I had kind of like the same problem but it will only pulsate like 3~5 times. Abter a PS flush and a brake flush it went away... now my AC compressor and the belt pulley is F*** up from pulley stress...

bguild

Guys, I'm coming closer on fixing this. I am fairly certain it's the pump. BTW, the cost of a new pump from Lexus is $2500. I happen to have found a used one for 1/10th of that cost.

Brian

savanna13

All this for traction control?

bguild

You are seriously asking that question? You own two 1 Gen GS's.. you do not work on your cars? Personally, I can't stand anything being wrong with my car, and I find it fun to fix problems on it. Maybe I am in the minority here, it's been pretty difficult finding technical knowledge on this forum. This forum is mostly about lowering springs and new wheels. Which is sad.

Kaiser

iTrader: (1)

I don't think many of us HAVE traction control and the ones who do usually wish they didn't. So it's difficult to give you any experience on the subject. Being that I don't have it, I really just skipped over this thread. If you want to PM me your email address, I'll send you the pdf pages from the 95 Supra which appear to be extremely similar to what you have going on.
I applaud you for your contribution, but there are threads on other topics here. It's just that most of the info gathered here, was retrieved from somewhere else. Let's face it, the first gen isn't the most popular car to 'personally' wrench on.