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Abs/tcs Lights - This Is Different Than Related Posts

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Hey guys, This is my first post but been lurking for a few months now.. My background is more turbo'd vehicles. I belong to a club "SDAC" Shelby Dodge Automotive Club, and use to have a couple turbo dodges. One being a 1987 Shelby Lancer # 148 of 800. Turbocharged 2.2 liter with a 5 speed running 18lbs of boost. I learned how to "burn" my own computer (LM) chips. This car was my first experience with vacuum solenoids. It's funny, I read a post on here about swapping in cams from the 2.5 n/a engine. That actually was the biggest "bang for the buck" mod we use to do to our cars.. You couldn't purchase a custom grind that was better than that swap, without 20k in mods to your car. I wish something would have happened with that "thought". If someone had a set of cams to donate, i'll do it. I'm going to be picking up a complete engine at a local yard with 70k on it for about 500 bucks.

I have a buddy that is into the Grand Prix's, who does his own tuning an such. I was trying to pick his brain for a bit then after a while realizing these two cars are almost nothing alike.

Anyways, I always do all my own work on all my cars (within reason). I do however, have a cousin that runs a local speed shop part time and have access to a chassis dyno which I'll like to get time on this spring.. For now, I just want to get this pig running issue free..


So on with the questions..


I have a 99 Millennia S , whereas the "ABS" and "TCS/TCS Off" dash lights don't ever go off. From the time I turn the key on, 'til I turn it off.. I have the 96 Service manual and apparently the ABS system was changed between 96 and 99.. I'm having a hard time locating a diagram so I can pin out the wheel sensors, the abs motor and what not.. I did find the connectors for the front wheels and got like 1395 ohms on one and 1322 on the other.. unfortunately I'm thinking the issue is more critical than just the wheel sensors. The PCM doesn't even give the abs system time to fault because the ABS light is always on.


So with the ABS being faulted, obviously the TCS is faulted.. so I'm sure you all know when I step on the throttle (if engine speed is below 2500-3000 Rpms) the engine seemingly cuts out, sometimes stalls.. However if I keep my foot in it, the engine tries to rev back up (SuperCharger screaming) but feels like I'm towing a house..


I do have erratic idle issues as well among others, which I am slowly chipping way at. Praying to god that it isn't the IAC.. I know there is a solenoid that controls "high idle" but it seems to check out ok. Amazingly I think my SC is ok. I have a little bit of oil trace in the CAC and front intercooler but not dripping, and no pooling inside the SC. I have replaced a couple solenoids, all the 4mm vac lines, zip tied everything, sprayed everything with ether, to check for leaks (something we use to do to check for leaks on our turbo cars)


So I know this is long, but for those of you who skipped right to the end, I''m looking for a ABS/TCS wiring diagram, possibly the diagnostics sheet. Or a way to trick the PCM into thinking the ABS is functioning correctly..


Thank you



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I have been talking to the guys at DIYAutotune.com, the makers of Mega Squirt. I know they have a few units that work with some more popular Mazda's to give them a standalone fully tunable PCM.. Unfortunately they would need a group buy of at least 20 to make any moves, and I don't think we have the interest..


I am also working on utilizing a single coil, they sell for about 70 bucks, that has a higher output than stock and even higher if you pair it with a hot ignition system. It's able to be wired for our firing order I just need to work on wiring it in. I thought some might take interest in this.

I also have picked up a couple 12 volt solenoids I'm going to try to mount remotely. I just have to make sure the "Ohm's" would compare to the stock units coils and won't trigger a code..

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Welcome to the forum.


The Miller-cycle engine is pretty unique with many trying different things over the years. A full custom 2.5" exhaust, high flow cat, good muffler, intake and chip provide the most power as it really lets the supercharger breathe.


My first instinct would be the ABS sensors but you've already addressed that. Other possible causes are the temp sensor within the transmission or transmission itself. When its below ~20 degrees the TCS light will remain on solid, then as it warms goes off. This is some sort of fail safe and its possible the fail safe is stuck in a single position (albeit rare)


Wheel speed sensors or something with in that system would be where I would take a hard look. If a Millenia S is ever put on the dyno the ABS and TCS light will remain on solid and generally do so for a few miles until ECU see's equal movement all around. It may still produce voltage if being tested but without hooking up a data logger that logs each wheel independently you'll never know if its the correct voltage.


We all loves our's Millenia's, but even before I began collecting them speed was never an easy task.


JET makes an excellent custom tune ECU, cam swap's have been discussed, smaller pulley is good for 5hp or so, custom headers with removal of pre-cats. Larger AMG style s/c, and of course No2.


A handful of people have managed to swap in a 5-spd transmission as well.

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I appreciate your input BHR. Do you think a bad wheel sensor would cause the lights to stay on all the time? Even if I attach my Diag Tool and use it to clear the codes, they don't go off. That's why I was curious if it wasn't a larger issue.


However, you are the "go to guy" so I will look into that today.


Thank you

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I pulled the abs codes I had a right rear sensor bad and a failsafe relay. I rung out the relay with a VM and tested it with 12 volts. Everything checked out. So I cleared the codes and we'll see if it comes back.. I am almost 100% certain I don't have a Vacuum leak.. but who knows, it wouldnt be the first time I was wrong about something.. just ask my wife..


I did find 2 timing idler pulleys had peeled off their "jackets" so I'm rocking the naked bearings... My tensioner is shot so it's been modified to accept a 5/8ths bolt, ..aannndd it still "auto" tensions..lol (Just a temporary "to get you home" fix..) so until I get my parts to fix the timing issues I wont know for sure..


Tell me about the smaller pulley and the larger AMG SC... I was going to attempt to machine my own pulley because I wasn't able to find an aftermarket one..

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  • 1 month later...
I'm sorry for not getting back promptly. I am still having issues. I have replaced every single vacuum line and zip tied the 4mm ones. The larger lines all have hose clamps on them. Once in a while I'll get a code for an o2 sensor/ a false reading. then it fixes itself.. With it being so cold outside the car usually doesn't have any issues until it gets warmed up.. my thinking was the hoses were getting warm and loosening up (the reason for the hose clamps).

After the car gets warm then the issues happen.. if the car is below 3000 rpms it "feels" like there is a brake on the engine. If I'm just starting from a complete stop, it'll stall the engine. if I'm moving at a moderate pace, the you can hear and feel the engine bog down and not go any faster.. however, if I keep my foot into the throttle the engine will fight it. I also noticed recently that after i'm above 3000rpms and I go WOT, the boost gauge jumps to 10-12 psi and jumps around almost like the knock sensor is working...

So lets just entertain the idea for a minute that I'm not crazy and the vacuum lines are all great. Is there any other possibilities such, fuel injectors, pump etc.. I think BHR stated somewhere there is a sensor in the trans. can anyone confirm this?

.. again thank you guys for your help.

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