abs c1287 and c1288

[proc360]

Hi, I have a 98 STS. Love the car, just got it 2 months ago. I have these codes ABS c1287 c1288 RSS c1738. Now my question, can I use a used steering wheel position sensor from the scrap yard. Also the air compressor for RSS c1738. Should I wait and do the steering wheel position sensor first then check the codes before getting the air compressor. I added a new ground to the BPMV pump motor to clear codes c1242 and c1243. It worked. Got that repair from this site. I have checked all fuses and relays to ELC. I have cleaned and checked the connections to the steering wheel position sensor it there anything else I should try. Thanks

[Cadillac Jim]

There are two grounds for the EBTCM module and pump. One of them is through the wiring harness and is for the electronics, and is necessary because of the relays in the EBTCM. One of them is directly from the back of the pump motor to the engine block or chassis ground. That is apparently the ground that was bad or missing and caused the C1242 and C1243 codes, and that you fixed by adding a ground.

You might want to check for the location of the short causing the C1738 with an ohmmeter before you buy the pump assembly. If it's in the wiring harness, a new pump assembly won't fix it. If it's a HISTORY code, it's intermittent, which makes me think of a short somewhere in the wiring.

[proc360]

Thanks,the C1738 is a current code not history. I did take the pump down and checked it on the bench. Which I did not mention on the last posting. The pump worked when I put voltage to it,I cleaned the ground that was going to the rear of the pump. I checked the connector (4 pins) which had constant voltage and good ground. I will check the wiring as you suggest. What is your opinion regarding the steering wheel position sensor?? Is that an item I can get used or is it necessary to buy new?? Thanks again.

[Cadillac Jim]

I've never had a steering sensor problem myself. My personal opinion about sensors is that they are relatively inexpensive compared to my time and effort, or the cost of a mechanic's time and effort, so I always get new OEM parts for sensors.

But, the 1997 FSM clearly states as a starting point in diagnosis for DTC C1287 on page 5E2-182 "It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction." At the beginning of the pages on DTC C1288 on page 5E2-186, there is a bullet under "Condition For Setting The DTC" that says "An open in circuit 1763 or 1764 will set DTC C1288." These circuits are the LT GRN and LT BLU wires going between the SWPS and the EBTCM. On the next page, the warning to inspect the wiring first is repeated, word for word.

There is an interesting note under "Diagnostic Aids" for C1288: check the wheel alignment. If the car is pulling to the left or right, the Stabilitrak sensors can set this DTC. The last note in this section is "An intermittent malfunction [read: persistent HISTORY codes] is most likey caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation."

So, the FSM has multiple strong hints to check the wiring and connectors first. My personal opinion based on my own experience as well as many observations of threads on Caddyinfo is that most intermittent problems are due to loose connectors, but that damaged wiring does cause undercar problems. But if you do need to replace the steering wheel sensor, I would go with a new one.

[proc360]

Thanks, will do at first at opportunity. Will keep u posted. Have a happy holiday.