Any difference between NB1 ECU's for ABS and non-ABS cars? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


ECUs and Tuning Discuss Engine Management, Tuning, & Programming

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 05-21-2015, 10:37 AM   #1
Senior Member
Thread Starter
 
Join Date: Dec 2007
Location: ATL
Posts: 728
Total Cats: 48
Default Any difference between NB1 ECU's for ABS and non-ABS cars?

The reason I'm asking is because I've swapped over all of my "special bits" from a bent '99 (10AE w/ABS), into a straight '00 chassis (w/o ABS) - long story but you're welcome to read all about it here. Basically, everything from the '99 - including the ECU - went into the '00 chassis.

The car is working now with one exception...I keep getting a MIL (P0500), and several of the ECU "readiness monitors" won't go "Ready". The speedo works just fine, but the ECU registers a P0500 (VSS malfunction). With that MIL, the ECU registers "Not Ready" all the time and I can't pass the OBD check.

After tons of reading I'm beginning to wonder if the ECU from my ABS-enabled car is looking for signals from the wheel sensors where there currently are none. But I've pored through wiring diagrams and I can't find anything from the ABS system that feeds into the ECU! In fact, everything I read says that the ABS system is completely separate from the ECU (and I'm tempted to believe that).

However, another data point this morning was when I (finally) displayed the "Speed" signal from the Torque app on my tablet. Lo and behold, it shows zero all the time - even when the speedo registers a speed!!

So...back to the original question; is there a difference between ABS and non-ABS ECU's for NB1's?
rwyatt365 is offline   Reply With Quote
Old 05-21-2015, 10:46 AM   #2
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,165
Total Cats: 2,573
Default

Have tested and made sure the actual speed sensor on the transmission is connected and working?
18psi is offline   Reply With Quote
Old 05-21-2015, 10:52 AM   #3
Senior Member
Thread Starter
 
Join Date: Dec 2007
Location: ATL
Posts: 728
Total Cats: 48
Default

It is connected, and the speedometer in the dash works just fine (no fluctuations, no dead spot, and is within 5% of the GPS speed).
rwyatt365 is offline   Reply With Quote
Old 05-21-2015, 10:53 AM   #4
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,165
Total Cats: 2,573
Default

Weird.
Both of them Fed-Spec cars?

swap ecu back and see? 99-00 doesn't have immobilizer so should be easy
18psi is offline   Reply With Quote
Old 05-21-2015, 10:57 AM   #5
Senior Member
Thread Starter
 
Join Date: Dec 2007
Location: ATL
Posts: 728
Total Cats: 48
Default

Weird indeed!

Unfortunately to '00 was just a bare shell - no ECU to swap back to ("testers" will be graciously accepted )
rwyatt365 is offline   Reply With Quote
Old 05-21-2015, 12:01 PM   #6
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,990
Total Cats: 1,457
Default

access to an oscilloscope? Probe the speedo out signal and see what it looks like.
aidandj is offline   Reply With Quote
Old 05-21-2015, 01:14 PM   #7
Senior Member
Thread Starter
 
Join Date: Dec 2007
Location: ATL
Posts: 728
Total Cats: 48
Default

Got a cheapo scope, will try to scope them tonight.
rwyatt365 is offline   Reply With Quote
Old 05-22-2015, 09:00 AM   #8
Senior Member
Thread Starter
 
Join Date: Dec 2007
Location: ATL
Posts: 728
Total Cats: 48
Default

The verdict...sumpin goes in, nuttin comes out...

...of the instrument cluster...

What does that mean? The VSS on the trans is good; took it out and it generates a signal at the connector. Put the VSS back in and checked continuity to the dash - checked good. Put the car on the hoist and hooked the scope to the leads from the VSS (1M and 2M), and got a good signal turning the wheels.

THEN, connected the scope to the "speed" output from the instrument cluster (2L), and got...nothing. So, somewhere in the bowels of the signal conditioning in the IC, the speed signal gets "lost".

Time for a new IC...
rwyatt365 is offline   Reply With Quote
Old 05-22-2015, 11:19 AM   #9
Junior Member
iTrader: (9)
 
Join Date: Dec 2011
Location: SFBay
Posts: 339
Total Cats: 39
Default

Unfortunately, it's probably your odometer unit, since that converts the VSS signal.
I would be happy to send you a spare for testing for the cost of postage. PM me.
scenturion is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
1.6 clutch/flywheel on 1.8/6spd concealer404 Suspension, Brakes, Drivetrain 8 09-17-2015 01:04 PM
Bp5a swap NA8 Will_da_beast Engine Performance 1 09-14-2015 08:06 PM
WTB parts for HPDE car Voltwings WTB 5 09-11-2015 09:23 AM
Sold fail wagon Miata parts for sale/trade 2 09-07-2015 09:51 PM
ME221 Now has Autotune and Long Term Fuel Trim Tables Motorsport-Electronics ECUs and Tuning 0 09-05-2015 09:02 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 07:42 AM.