KevinRR

Working on my dads 97 vette. Has had repeating codes c1233 for RF wheel sensor circuit open or short.

I read the writeup on here via search, regarding the connections on the wiring harness ends for the wheel sensors. I removed the harnesses from both wheel sensors and swapped them and still got the same code.

I removed the RF hub assembly and pried the metal cover off the back. wiped off the wheel sensor and the rotor on the hub. Put it back together and put it back on the car.

I also took a small screwdriver and gently bent the pins in each end of the wiring harness connectors, to make a better contact. I used dielectric grease on the connectors and plugged them together tightly.

Then I cleared the codes and went for a drive. The code only returned once I hit a hard bump. I cleared it again and it didn't return for the rest of the drive.

Car has sat for about a week waiting on parts. Today the abs/tcs code was back even though the car hasn't moved and it didnt have the code when I shut it off.

I think this is more likely to be the wheel sensor itself, but what do you all think? Could it still be the wiring harnesses/connections?

The sensor/hub assembly is about 160 at the auto parts store. How much do the wiring harness(es) cost? There are 2 on the right side...a short one from the wheel to the subframe, and a longer one from the subframe to the front of the engine where it plugs into the main harness.

Any advice (that I havent already tried) is appreciated.

KevinRR

anyone?

KevinRR

Appreciate the heck out of all the help, guys.

Bill Curlee

Call me PM SENT.

BC

Jnape

Be careful using dielectric grease. It can actually inhibit a proper contact with a poor contact path in the connector. Read a post where the OP greased his contacts in his ignition switch repair. He had more troubles with the switch after. Cleaned the grease out and the switch worked properly.

Bill Curlee

100% on the mark! If you want to protect the ELECTRICAL circuit from oxidaction, corrosion, and frett corosion,,,you need a product like this:



Its NOT the only product on the market but it does work very good to prevent this sort of issue. Look for a designed product that will not effect the electrical circuit contact/connections.

I never liked using silicone dielectric grease for the purpose of contact protection. I use it for O ring lube.

BC

cliff_ford

A dielectric is an electrical insulator that may be polarized by the action of an applied electric field............. So not much use on connectors.

Bill Curlee

There are more female connectors that go bad than just the jumper cable.. Disconnect the jumper from the connector on the frame (Inboard of the wheel) and examine it.

Its female and it goes bad a LOT! Thats the one that gave me fits.

BC

KevinRR

I already examined/bent the female pins on both jumper cables plus the connection from the right sensor harness where it plugs in near the crank pulley. The terminals themselves all looked perfectly clean, just as you'd expect from a weathertight connector.

I have gone ahead and ordered 2 front wheel hubs/sensors. I checked locally and one was $160 so I asked dad and he approved the purchase. We also decided to get him some nice rotors and pads, which I had to get online. I looked and I could basically get 2 wheel hubs/sensors online for the price of one locally, so I went ahead and did that.

While I am in there I will use contact cleaner and spray out the dielectric grease since you guys think it will do more harm than good.

After that, I guess IF the issue returns it will be either in the wiring or the control box. From what I've searched on here ABSfixer will not repair a pre-2001 box and there's no damn way dad will spend a $700-1000 on a new one, so if that is the problem I guess it is a moot point anyway.

KevinRR

BTW, thank you very much Bill and others for the opinions. I worked all day yesterday and today trying to finish a single turbo rx7 install so I got no chance to check on the vette issues.

Bill Curlee

Other than a bad wheel bearing or mechanical damage to the wiring,,,since 97 to now,,,I have never seen a speed sensor fail. There pretty bullet proof.

Try this:

Obtain a AC Volt meter. Jack up the wheel and use the AC Voltmeter to measure the output of the WSS . It will give you a 0-5 VAC signal. The faster you spin the wheel, the geater the output.

You can disconnect the EBTCM main connector and read EACH wheel from that connector. That way you can insure that the WSS is getting the voltage to the main connector. You can also read the resistance of each WSS. It should be around 1000 ohms -1200 ohms.

BC

KevinRR

Well, I got the 2 new wheel hubs/sensors installed, and also rechecked the female connector ends and cleaned off some of the dielectric grease I applied. I drove his car around for 2 days. I hit every bump I could find in town (since he reported that the lights came on after hitting bumps, and it did this to me one time as well) and no codes, no abs/tcs lights after that much driving. I decided it was probably fixed.

Jumped in it today ready to take it back to dad's place after fixing a laundry list of issues, and as soon as I started it up the abs/tcs lights/warnings were on and I had the same code 1233H.

The lights were NOT present when I last drove/shut down the car. I cannot understand why twice now, the code shows up on startup and not while driving.

So it has to be either the wiring, or the EBTCM.

I have read here that ABSFIXER does not work on the pre-01 EBTCMs, so I guess if it is that then we are just SOL. I did read one post that mentioned resoldering the points on the circuitboard, so I might give that a shot.

I dont see how it can be the wiring, none of it is damaged and I did bend the female terminals to make better contact with the male ends. IF the harnesses on the passenger side are not too much money I may replace them just for the heck of it.

I considered doing the test mentioned above by Bill, but it seems to me that the issue causing this must be very intermittent and it would be unlikely I could 'catch it in the act" so to speak.

Right now, the information/advice I am looking for is:

1) Roughly how much are the short jumper harnesses between the wheel sensor/hub and the subframe connectors? how much is the middle harness between the passenger jumper cable and the main harness connector in front of the crank pulley?

2) how common are internal issues in the EBTCM? Has anyone repaired a similar recurring short/open wheel sensor code by replacing or repairing a 97-00 unit? IS a used unit worth a try?

Where is the EBTCM located on a 97 anyway? I don't have an FSM for the car...

Bill Curlee

Your best bet for GM parts is Gene Culley www.gmpartshouse.com Gene will beat your local dealer parts price hands down!

Check Genes website or call him.

Bill

KevinRR

Are the wires in this circuit special/shielded? Is there a reason I cannot use new automotive wire for troubleshooting purposes? If the wiring and connectors in the system are this suspect (and were within months of the car being produced, from what my searches have yeilded), it doesnt seem wise to spend good money putting the exact same new suspect parts back on.

I plan to investigate the ebtcm next, for corrosion at the connectors and possible issues with the solder points.

Bill Curlee

The wire is just plain ole copper stranded wire. The female connector terminals are normaly the issue and make POOR connections. Heres a GOOD and BAD female wheel speed sensor main harness connector.

The Connector on the LEFT is NEW and the one on the RIGHT has BAD female pins:



If the connector female pins are good,,,the wire on the back of the connector can be broken at the pin or somewhere on the wire;





BC

KevinRR

Thanks Bill. I read the ENTIRE electrical thread and saw those pics many times. I already went through and took a small screwdriver and bent the tabs on the female plug terminals down to make better contact.

My line of thinking is...if those connectors are SO suspect, and were known to go bad within just a few years of the car being new, why spend the money to put the same (new) parts back on the car? I'm thinking of re-engineering the wiring connections to rule out the wiring as the issue. I was asking if the stock wiring was shielded or in some way special, but since it's not then there's no reason not to re-engineer that part.

Thanks for your help as always sir.

KevinRR

After searching for weeks on this and other subjects I noticed that almost no one on this forum ever updated their troubleshooting threads with their "fix", so I wanted to add to this one.

After replacing both wheel bearings/hubs/sensors with new ones I still had intermittent codes. Obviously the issue was either in the EBCM or the wiring.

I checked everywhere about the EBCM. No one wants to repair a pre-01 version. This car is a 97, and to make matters worse it is 97-only. There is actually a local shop that does nationwide electronics repair, that claimed they could repair and warranty the 97 ebcm, ( FOR 500 BUCKS!!!!!!!) but getting straight answers from them was like pulling teeth and they didn't act like they really cared if I gave them my business or not so I decided not to fool with them.

I went ahead and pulled the EBCM off and resoldered all the points on the board, which took about 25 minutes max. Basically I just reheated the solder until it pooled, then wiggled the metal pin/terminal. In points where there didnt seem to be much solder, I added some of my own.

Then I moved to the wiring. Only one sensor was giving me a code. There are 2 of the troublesome female connectors on that side...so assuming that the issue could be on one or both, I cut them both out. I snipped the connector on the wheel sensor off, leaving the 2 wires there. Did the same on the connector at the subframe. Then used my own 16 gauge wire, solder, and heatshrink insulation, and I wrapped those 2 new wires around each other as I routed them along the control arm etc. just as the factory wiring is wrapped around each other.

I went that route, instead of a new jumper harness, not because I was being cheap, but because if those female connectors are SO problematic, then I didnt feel it would be wise to put another set back on the car, especially given what GM charges for them/the harness.

Cleared the codes and went through about 6 or 7 drive cycles, at least 50 miles, and no codes. So far, so good, gave the car back to dad today and told him to let me know if it comes back.

Bill Curlee

Well done my friend!!! You were very wise to save your $500.

Bill

1999_TRC

Did you void the warranty on the new bearing assemblies when you cut off the connectors?

KevinRR

Who cares, they cost a whopping $75 shipped each. Plus we still have his original bearings/sensors which are probably still fine too.