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Help requested with P1590 '01 Bosch

4499 Views 7 Replies 4 Participants Last post by  rbelshaw
"P1590 ABS rough road signal circuit malfunction LR Description: Hardware is OK but SLABS ECU is sending an error signal"
I am throwing no ABS codes, and checked all wiring, connections, grounds and tapped the sensors to insure they were fully seated. I interpret the code as saying that all hardware is functioning normally, but the ABS ECU is sending a spurious signal to the engine management ECU. (This is a "P" code, not an ABS code) From my research the rough road circuit is designed to tell the ECU to disregard fluctuations in the crankshaft sensor so timing is not effected on rough roads. I have cleared mine several times, but it reappears after each drive cycle. In California, this code will cause you to fail the emissions test. Its the only DTC I have left to fix.
The code comes up on the search function, but no one ever discusses how, or if, they resolved the issue. I suspect, in the absence of a bad ground/ connection, the ABS ECU is toast.
Any help would be appreciated... Thanks
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Deranged ABS ECU. Swapped out for a used one, ABS and TC dash lights went out for the first time in years. I kind of miss my two amigos. Codes cleared, Drive Cycled, smogged and tagged legal to drive by the California Republic. On to the heater o-rings....
Good deal on the ABS ECU!
Throw an Audi heater core in there and get rid of O rings permanently. Just did the same thing in a Disco II, but took a little extra work to accomplish it.

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Thanks Marty- I am seriously considering the Audi replacement, because I hate working on or under a dash and would prefer to go there only once. Not that is likely on these cars. And some possibly useful information- The widely available ABS ECU part number ending in 500 appears to be the same as that ending in 501 installed in the later cars. The Hollander manual apparently does not list it as an interchange. I have, however, not road tested the TC or the ABS. That will happen after I do the brakes this weekend.
hmmm Marty? you mean Martin?
I'm sure there are members that could come up with a few other names for him...
Was about to say, I have been called a LOT worse!
OP, there is also a Marty here, so it can get confusing with the names, and my name is actually Martin....

Martin (see!)
Apologies. Posting before coffee. Always a bad idea, like posting after wine.
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