Diagnotic Codes

[vdwarren]

Im getting a TC0025 and a TC0027, im tired of looking at my anti lock and traction lights..... when i start driving, they come on at random points.

Anti lock and Traction Conrol lights on when I start driving. Just replaced Left Front wheel sensor and hub. Checked and manipulated harness connections. Same codes showing. Once in awhile when almost stopped the left front brake acts like it wants to grab, then works OK for a while. All help and suggestions very welcome. Limited income so a dealer shop has to be last resort.

[Ranger]

One code is a sensor fault. The other is a continuity fault. Usually one in the same, but you might check the plug and circuit. Maybe a chaffed wires somewhere.

[Cadillac Jim]

The 0025 and 0027 aren't OBD II codes. From my OBD I list, I have

T025 LF Wheel Speed Sensor Fault

T027 LF Wheel Speed Sensor Continuity Fault

These codes indicate a wiring problem. Take the connector off and look into it, and tighten the connector if necessary.

Your protocol says 1996 SLS. Are you sure that it's a 1996? OBD I codes were last given in 1995. A 1996 VIN number will look something like this:

1G6KS52YxTUnnnnnn

where X is a check digit and nnnnnn is the serial number. The year code is the T. If it's an S, your car is a 1995.

[vdwarren]

The 0025 and 0027 aren't OBD II codes. From my OBD I list, I have

T025 LF Wheel Speed Sensor Fault

T027 LF Wheel Speed Sensor Continuity Fault

These codes indicate a wiring problem. Take the connector off and look into it, and tighten the connector if necessary.

Your protocol says 1996 SLS. Are you sure that it's a 1996? OBD I codes were last given in 1995. A 1996 VIN number will look something like this:

1G6KS52YxTUnnnnnn

where X is a check digit and nnnnnn is the serial number. The year code is the T. If it's an S, your car is a 1995.

[vdwarren]

Im getting a TC0025 and a TC0027, im tired of looking at my anti lock and traction lights..... when i start driving, they come on at random points.

Anti lock and Traction Conrol lights on when I start driving. Just replaced Left Front wheel sensor and hub. Checked and manipulated harness connections. Same codes showing. Once in awhile when almost stopped the left front brake acts like it wants to grab, then works OK for a while. All help and suggestions very welcome. Limited income so a dealer shop has to be last resort.

Thanks for the speedy reply Jim. Serial # 1G6KS52Y1TU834930. Is there a particular harness connection that you suspect? Gratefull for your help.

[Ranger]

Those ARE OBDI codes. I think early '96's where OBDI and later where OBDII. We generally consider '96 as OBDII, but I believe the break point was somewhere in mid '96.

[Cadillac Jim]

My 1997 FSM, page 8A-44-2, shows only two connectors in the line to the LF whee speed sensor, the one on it and the one to the EBTCM. I would check both. Pull them off, look for connectors pushed into the jack, loose or bent connectors, or dirt and grease. I would try the small two-wire connector on the left front first because that is the one that was off. Look for problems with the wires themselves, then if the problem persists, look at the connector to the EBTCM.

[vdwarren]

My 1997 FSM, page 8A-44-2, shows only two connectors in the line to the LF whee speed sensor, the one on it and the one to the EBTCM. I would check both. Pull them off, look for connectors pushed into the jack, loose or bent connectors, or dirt and grease. I would try the small two-wire connector on the left front first because that is the one that was off. Look for problems with the wires themselves, then if the problem persists, look at the connector to the EBTCM.

[vdwarren]

My 1997 FSM, page 8A-44-2, shows only two connectors in the line to the LF whee speed sensor, the one on it and the one to the EBTCM. I would check both. Pull them off, look for connectors pushed into the jack, loose or bent connectors, or dirt and grease. I would try the small two-wire connector on the left front first because that is the one that was off. Look for problems with the wires themselves, then if the problem persists, look at the connector to the EBTCM.

Thanks "Jim" & "Ranger" for help.

In checking for connectors as sugested, I pulled the soft cover next to aircleaner, exposing fuses and the relay center, I am not identifing the EBYCM. I have a run of the mill manual, it shows the location to be in the left front, if so I am not recognizing it or I have not found a way to uncover it. I am trying, bear with me guy's.

[Cadillac Jim]

The EBTCM probably isn't where the problem is. Check the connector on the LF hub first, then the wires. Also, I would use an ohmmeter to check the hub sensor to make sure it's good. If everything checks good after that, then you look at the EBTCM and its connector.

The Electronic BrakeTractionControl Module (EBTCM) is underneath the PCM. It's tucked behind the radiator mount on the brake pressure modulator valve. From under the car, follow the brake line to the modulator valve, and the EBTCM is on top of the valve. The valve is mounted on the front suspension subframe low against the far driver's side.

There is a picture on page 8A-201-f, Figure 10, but I can't make out excactly what some of the sourrounding pieces are, unless they are the supports for the engine compartment fuse/relay center box. I couldn't see into my car well enough to recongize the parts in the figure.

[vdwarren]

The EBTCM probably isn't where the problem is. Check the connector on the LF hub first, then the wires. Also, I would use an ohmmeter to check the hub sensor to make sure it's good. If everything checks good after that, then you look at the EBTCM and its connector.

I'll edit this post later today with the location of the EBTCM from my 1997 FSM.

Jim, went back on that connector, "just installed new left front hub & sensor last week" That two wire harness goes thru the fender well and has connector just in front of the master cyl., then incorporated into a large harness that runs down between engine and firewall. I checked the continuety of the two wire, and checked fine, "no drop at all".

My meter may not be sensitive enough on the ohm. readout, when checking resistance of the wheel sensor it self, I could not get a reading, maybe a slight needle waver. Same with the take-off sensor.

[Ranger]

Set your meter to "continuity" and test the hub sensor again. If you have no continuity the sensor is bad.

[vdwarren]

Set your meter to "continuity" and test the hub sensor again. If you have no continuity the sensor is bad.

Thks for reply Larry, did check again with no resistance reading at all, on the old take-off, and the new one just installed.

The report at the shop that replaced it said that the old one tested ok, and said the replacement really was not necessary, but I elected to stay with the new that was installed. So, I will have to retrace steps and get thier diagnosis clearified.

They gave me a read-out from: ALLDATA Online - 1996 Cadillac Seville SLS V8-4.6L VIN Y - Electronic Brake and T... http://alldatapro.com/alldata/PRO~V7079342.../0/41746574/4...

Your comments are certainly welcome and very much appreciated, if I do not hear from you, in any avent, I will let you know what results. Vern

[Ranger]

Very strange Vern. How could they say that the wheel speed sensor is good if there was no continuity? You did test the sensor connection on the hub as opposed to the plug, correct?

[vdwarren]

Very strange Vern. How could they say that the wheel speed sensor is good if there was no continuity? You did test the sensor connection on the hub as opposed to the plug, correct?

No, Larry, did it at the plug. What surface's on the hub assembly should be used? I am certainly a novice at this type of testing, please bear with me.

[Ranger]

Check the backside of the hub, Vern. Unplug the wire and check the connection ON the hub, not the plug. The two pins on the hub will tell you if the sensor has continuity. Checking the plug tests the circuit back toward the PCM.

[vdwarren]

OK, Larry, I hope I am getting up to speed with you. The take-off assembly has no continuety between the housing with the sensor and the hub. The new one installed indeed has continuety. ( Strange that the shop would report that the old one was still good, except, maybe that the new one still didnot correct the problem.)

I think I mentioned that every symptom was the same after the installation. I have checked the connections and the integraity of the wire harness at the points that where exposed, but not the connection at the EBTCM.

Is there a factory correct way to clear codes on the OBDII?

I hope there will be a time that I can resipricate for your help.

[vdwarren]

On previous questions, I asked the correct method to clear codes on the OBDII, but, Jim feels that the system is a OBDI, with the codes that it was showing, although the serial number is a 1996.

Still want to clear the codes.

[Ranger]

The switch to OBDII was sometime in '96. I think on your car you simultaneously press & hold the OFF & PASSENGER WARMER buttons. Once in the diagnostic mode, the DTC's should be displayed. After that, HIGH FAN = YES and LOW FAN = NO to the prompts. Answer no till you see CLEAR CODES?

[vdwarren]

Well, Larry, the codes cleared fine. Put all back together and still have T0027.

I guess my only option is to find a Cad. Dealer that has a reputable rating.

This car is like new, interior, and a few dings in the paint, runs good at 111,000. depending on estimated repair may have try to replace it with something less complicated. We have to use it for our transportation, it seems to run well as usual, but the Trac & ABS light glaring at me.

Really appreciate the help and time that you took to help me, anything that comes to mind, please let me know. Vern

[Ranger]

Have you checked to be sure you do not have a chaffed or broken wire somewhere from the wheel speed sensor? I still have a nagging feeling that it is just a bad sensor (hub assembly).

Depending on the repair estimate, you could just put a piece of electrical tape over the T/C & ABS light so as not to bother you and drive it like the cars you learned to drive on (without T/C & ABS).

[Cadillac Jim]

The resistance of the wheel speed sensors is 850 Ohms to 1350 Ohms. Check it at the connector to the wheel. There should be an open circuit from either connector to the hub. If it doesn't pass this test, the wheel speed sensor (WSS) is bad.

Reference is the 1997 FSM page 5E2-79 regarding OBD II DTC C1232 and many other places in sectio 5E2.

[vdwarren]

Thanks you guy's for the comeback, you are clearing up questions that should help when I take the car back into the shop that installed the new sensor.

I pulled the wheel again, "esier to get to the connector", No reading from either terminal in the connector to the hub or wheel. As I stated before there is continuety from the sensor housing to the hub, but none on the old take-off.

The ohm resistance that you mentioned, that reading would be from the connector terminal to the whl. hub?

If it turns out to be a defective new sensor, that gives me hope, we love the car when all is in order.

Can't thankyou guy's enough.

[Ranger]

Vern, Pull the plug and forget it. You want to check the continuity and/or resistance at the pins on hub.

[vdwarren]

Larry, I can see why I seemed a pain in the rear. I purchased a digital meter, reading on new 1127 and the old 1041. I was measureing where you said, the old meter showed continuety fine but not resistance. Really sorry guys.