R34 GTT (ER34) ABS Failure

[GoHashiriya]

Was out for a drive in Tokyo with a fellow member this past weekend when my ABS, TCS and Slip lights came on. We did a test, and yep, no ABS. Scanned the codes and got 17 and 44.

Conveniently this has occured about 500kms after replacing the TCS motor on the throttle body; I've been plagued with a recurring code 17 and TCS motor failure for the past year, although it didnt really phase me until I realised I have shaken coming up in December and codes = failure. 

The TCS motor flap is still moving on startup and I'm hesitant to believe the replacement is causality, after all, it's just a plug and its operation (or lack of) never caused ABS failure before. All fuses are fine - checked visually and with a voltmeter - which then led us to the ABS system. 

As the ABS pumps and relays seem to be one unit and with used variants being two a penny on the auctions, I have taken a punt with a 2,000 yen (with warranty) replacement 47600-AA000. However, after some digging, I've come back with the following headf*ck:

Part Numbers:

47600-AA566

Latest revision of the pump and about 200k from Nissan. This is stated as being compatible with the ER34 RB25DE, RB25DET plus Silvia S15 and Stagea 34.

47600-AA500

Currently fitted to my car, looks as though it has been replaced at somepoint. Historical info is limited although I can confirm it was available for Silvia S15 and Stagea 34.

47600-AA000

Came on the ER34 RB25DE, Silvia S15 and Stagea 34. I can find no reference to it ever being fitted to the ER34 RB25DET, although it did come on the Stagea RB25ET.  

I have three weeks to get this fixed and was really hoping to get a final trackday in for the year before I turn the car back to stock-ish for shaken. So, has anyone had any experience with these ABS actuators and can confirm the interchangeability? Or even better, anyone had issues with the ABS system and managed to fix it by other means? 

We can feel the motor give some kind of response with the car on. It's getting power.

Car is running stock auto ECU. 

[GTSBoy]

I would Nistune the ECU, override the TCS motor/position code and forget the car ever had it. (in fact, that's exactly what I did, because Neo into R32).

What's code 44 again?

[GoHashiriya]

10 minutes ago, GTSBoy said:

I would Nistune the ECU, override the TCS motor/position code and forget the car ever had it. (in fact, that's exactly what I did, because Neo into R32).

What's code 44 again?

Exactly what @tsuokun said. Nistune isnt possible with the tight timeframe. Plus I'm of the camp that's too pussy to drive with ABS off.

17: ABS-TCS control unit circuit - Throttle control unit detects malfunction in the system. (open throttle sensor, harness, etc.) / TCS/ABS Control unit detects malfunction

44: ABS-TCS communication circuit - Malfunction (open/short circuit, etc) is detected in multiplex communication line between  engine and TCS/ABS

[robbo_rb180]

1 hour ago, GTSBoy said:

I would Nistune the ECU, override the TCS motor/position code and forget the car ever had it. (in fact, that's exactly what I did, because Neo into R32).

 

If unable to Nistune in the timeframe look at the ec/tcs/abs diagrams to see what voltage is required so no error appears. May be able to trick it with the right resistor/diode in the circuit as we did that on a mates r34 na +T setup to fake a few signals.

[GTSBoy]

1 hour ago, GoHashiriya said:

44: ABS-TCS communication circuit - Malfunction (open/short circuit, etc) is detected in multiplex communication line between  engine and TCS/ABS

Well, there's your problem. There is a bus wire/wires that connect the ABS and TCS CUs to the ECU. Yoou have a wiring problem there.

[GoHashiriya]

2 hours ago, GTSBoy said:

Well, there's your problem. There is a bus wire/wires that connect the ABS and TCS CUs to the ECU. Yoou have a wiring problem there.

Seeing as the system is untouched - bar the TCS motor - I'm wondering whether there is any particular part of it that's prone to failure. Searching in Japanese ive found some examples of people replacing the computer and the motor/pump to rid the ABS/TCS/Slip lights from the dash but they never go into detail. 

[GTSBoy]

The car and loom in question is >20 years old now, been through the hands of several possibly hamfisted dickheads. There are plenty of things that could go wrong, and it always turns out to be something from left field.

You have to go looking for the problem. It won't jump out at you and say "Here I am!".

[joshuaho96]

17 hours ago, GoHashiriya said:

Exactly what @tsuokun said. Nistune isnt possible with the tight timeframe. Plus I'm of the camp that's too pussy to drive with ABS off.

17: ABS-TCS control unit circuit - Throttle control unit detects malfunction in the system. (open throttle sensor, harness, etc.) / TCS/ABS Control unit detects malfunction

44: ABS-TCS communication circuit - Malfunction (open/short circuit, etc) is detected in multiplex communication line between  engine and TCS/ABS

Sounds like code 17 is just telling you to retrieve actual codes from the TCS/ABS control unit. You can either do it via Consult or by grounding the following pin with the key on but the engine off. Do not touch the brake pedal when pulling codes.

To clear the code after fixing things is going to take the following tap code if you don't have a Consult:

It sounds like code 44 is referring to a circuit signal integrity issue on pin 16:

There's a diagnosis tree but a lot of it calls for checking what kind of signal you get on the Consult. NDS1 does not support reading ABS codes or data unfortunately. I highly recommend getting the R34 Skyline service manual to help figure out what's going on here. It's possible your ABS control unit has given up the ghost and is spewing nonsense over the bus which is causing the ECU to throw codes. Also possible there's a harness failure between the ECU and the ABS C/U. I'm not omniscient so you're going to have to be the one to see whether it's a harness problem or maybe you need to recap your ABS control unit or something else.

[GoHashiriya]

1 hour ago, joshuaho96 said:

Sounds like code 17 is just telling you to retrieve actual codes from the TCS/ABS control unit. You can either do it via Consult or by grounding the following pin with the key on but the engine off. Do not touch the brake pedal when pulling codes...

I appreciate the level of detail in this, I was unaware NDS1 did not give out the entirety of the codes. We initially scanned it using the NisTune software from @tsuokun. That's where we pulled code 44. Actually, code 44 has since disappeared, and upon running the car this morning there were no warning lamps on the dash - which is of course more annoying.

I found a broken earth from the manifold to the strut tower, although this is likely unrelated.

You've given me a fair bit to go off so I'll review this and see what I can find.

 

[joshuaho96]

20 minutes ago, GoHashiriya said:

I appreciate the level of detail in this, I was unaware NDS1 did not give out the entirety of the codes. We initially scanned it using the NisTune software from @tsuokun. That's where we pulled code 44. Actually, code 44 has since disappeared, and upon running the car this morning there were no warning lamps on the dash - which is of course more annoying.

I found a broken earth from the manifold to the strut tower, although this is likely unrelated.

You've given me a fair bit to go off so I'll review this and see what I can find.

 

I would still try and pull the ABS codes, it's possible they're still in memory but not actively lighting the malfunction lamps. The ECU codes IIRC work similarly, even if the error goes away you can still read them via Consult with a counter indicating how many times the code was triggered. Intermittent issues like that would make me want to pull out the control unit first and foremost to check for dead caps. All of these cars are super old now and electrolytic capacitors all eventually fail on a long enough timeline.

[GoHashiriya]

Appreciate the info, first port of call will be digging for these additional codes. I may try to get ahold of a known working ABS computer from a friend and try the easy way of plugging it in to see if that works - I imagine the same could go for the actuator up front. 

Grateful used ABS computers and actuators are pretty cheap still, if I need one.

[GoHashiriya]

Thanks for the help @joshuaho96, pulled the codes today and got 36, rear left ABS sensor short. Then found what you see in the pic. 
 

Gonna get it on the lift this afternoon and attempt to sort it out. 
 

Fingers crossed may get next week’s track day in after all. 

[GTSBoy]

That's a mechanical problem that has caused an electrical problem. I see the damage on the end of the sensor, so presumably that's your sensor short. But it would appear to have been caused by the tone wheel moving axially out of position. It's supposed to be contained within the shield and aligned with the sensor. It's not.

[GoHashiriya]

3 hours ago, GTSBoy said:

That's a mechanical problem that has caused an electrical problem. I see the damage on the end of the sensor, so presumably that's your sensor short. But it would appear to have been caused by the tone wheel moving axially out of position. It's supposed to be contained within the shield and aligned with the sensor. It's not.

Yeah that's the one. Actually, appreciate this as I couldnt wipe the 36 code after and didnt think the signal wheel had made contact with the sensor - it had. I left the car at the shop and will have my mechanic switch it out this week. I know, it's an easy job, but I have zero time at the moment. Shaken is on the 5th. 

[GoHashiriya]

On 11/8/2022 at 12:24 PM, joshuaho96 said:

Sounds like code 17 is just telling you to retrieve actual codes from the TCS/ABS control unit. You can either do it via Consult or by grounding the following pin with the key on but the engine off. Do not touch the brake pedal when pulling codes.

Hey, where did you get the service manual in nihongo? My mechanic is asking for it. Searching in Japanese is like dating whilst deaf and blind

[Murray_Calavera]

I hope there aren't any issues with me posting this here. 

r34workshopmanualjap.pdf

[joshuaho96]

1 hour ago, GoHashiriya said:

Hey, where did you get the service manual in nihongo? My mechanic is asking for it. Searching in Japanese is like dating whilst deaf and blind

https://m.facebook.com/groups/gtrusa/permalink/886361081566908/?mibextid=Tuo9sz

[GoHashiriya]

16 hours ago, Murray_Calavera said:

I hope there aren't any issues with me posting this here. 

 

16 hours ago, joshuaho96 said:

https://m.facebook.com/groups/gtrusa/permalink/886361081566908/?mibextid=Tuo9sz

You're both absolute heros, thank you.