06 Pacifica ABS Issue (input signal missing & circuit failure)
 

Hello all,

I'm new to the forum but in researching an ABS problem for a customer's 2006 Pacifica I came across a lot of posts discussing a slough of ABS problems with these vehicles. I'm a little stumped here and I'd just like a second opinion before I go forward and spend more time without being able to give my customer an answer, and I certainly don't want to throw parts at this unnecessarily. The vehicle has about 100,000 miles on it and is in relatively decent condition overall, but is displaying an ABS light (traction control also). I checked the codes using my Auto Enginuity software and retrieved codes for both rear wheel speed sensors; both rear wheels are showing input signal missing and input signal failure. I checked voltage to and from each sensor, inspected the connectors, inspected the main module connector and found no faults. A test drive with the computer connected showed accurate and constant wheel speeds at all four wheels. Originally, I thought it was unlikely that both sensors would have failed nearly simultaneously but, I did find the TSB stating that sensors must be replaced in sets of four so, now I'm reconsidering that first assumption. However, I can't understand how the module is reading circuit failures and missing signals if it's still reading accurate wheel speeds...?

SO what opinion are u wanting?

I didn't really want to bias anybody's opinion by sharing my thoughts but, I'm thinking she must either have worn suspension components allowing the rear wheels to lose road contact, or the ABS module itself is malfunctioning.

U already know what to fix the TSB is there for this issue no need to scratch your head over something unless the TSB is not effective then look for else where. And no a worn suspension part will not affect any wheel speed sensor have u looked at one and how its mounted ? there is no moving part but a tone wheel on a hub or drive shaft that does dot dot dot as the sensor passes teeth.

Sure, the TSB states the sensors must be replaced as a set, but how can I get accurate wheel speeds from all four sensors if two of them are bad? I know how the system operates but, I don't see any bad wheel speed sensors. Since the tone ring is contained inside the hub it's not very likely that there's anything wrong with either of those. I can't, in good conscience sell this girl four speed sensors if I don't believe they're bad. Have you ever seem a bad wheel speed sensor provide accurate wheel speed readings?

do U have on a scanner the 4 wheel speed MPH? take it for a test drive and watch and see if one has a hickup then u will have your answer

Thanks for the help. I had done that when I first visited this customer (I'm also a mobile mechanic) and the scanner displayed accurate wheel speeds at all four wheels. However, I only drove about five miles that time. I just returned from the customer's home and I had her drive the vehicle while I watched the wheel speeds. After about 14 miles, the RR speed sensor began jumping around and settled at zero within about four more miles.

I already ordered a new set of sensors.

there ya go