Haldex Electrical Resistance Topic is solved

FattyArbuckle · Post by **FattyArbuckle** » 23 Feb 2016, 11:30

2006 XC70
I suspect that rear differential pump motor is starting to fail. I did your test of putting battery voltage to motor terminals & runs ok.

Do you know what the electrical resistance is supposed to be for both:
Motor terminal to terminal ?
Motor terminal to motor housing?

Thanks!

TonyatXeMODeX · Post by **TonyatXeMODeX** » 23 Feb 2016, 14:37

I tested a brand new pump motor terminal to terminal @ room temp. and had a value of 2.2 Ohms, from each terminal to housing it had infinite resistance. Remember that these values will change slightly with the age of the pump motor and temperatures.

FattyArbuckle · Post by **FattyArbuckle** » 24 Feb 2016, 04:53

Great - thanks for the info.
My suspect motor also has ~2.2 ohm terminal to terminal.
But, either terminal to housing is about 30K ohms. Wire insulation breaking down maybe?

TonyatXeMODeX · Post by **TonyatXeMODeX** » 24 Feb 2016, 07:15

Hello FattyArbuckle , 30 K ohms seems low, I tested an old faulty pump and the lowest reading I got was 260 Mega ohms. what are your symptoms ? No AWD ?, blown fuse in the REM for the DEM ?, Anti skid warning light ON ?, Do you have communication with the DEM ? Any fault codes posted ?.

FattyArbuckle · Post by **FattyArbuckle** » 24 Feb 2016, 10:58

Check Engine light was on.
Occasionally heard a “clunk” sound typically followed by ABS & Traction warning lights.
Although there were like 20 codes set, dealer could not find anything wrong.
Dealer cleared codes; Check engine light came back on the next day.
Car would not pass state inspection with Check Engine light on, so this was my first foray into CAN. (No CAN on the 245's !)
I went through the car and disconnected every module and in some cases used canned air to clean connectors. (My hope was that a poor connection was causing some CAN issues.) I borrowed a code reader and cleared the Check Engine light. (It was not a Volvo-friendly reader, so I couldn’t read the codes.)
Car passed inspection and Check Engine light has not come on for over 2 months.
Based on some snow-slipping, I think the car is front-wheel-drive only now – even though no warning lights come on.
Your info on the differential motor resistance seems to confirm that; I wonder if it fried the output section of the motor controller, but that is not causing any codes?
Differential motor replacement looks like a major job, so I’m going to wait until warmer weather before replacing this motor (and maybe controller?).
Any additional diagnosis suggestions are appreciated.
Thanks for your help !

TonyatXeMODeX · Post by **TonyatXeMODeX** » 24 Feb 2016, 14:14

To bad you can't confirm communication with the DEM because if there is communication then the DEM is still salvageable. If you are 100% certain that the AWD is inoperative then I recommend that you disconnect the connector for the pump motor until you can verify that there is communication with the DEM. This would eliminate the potential for damage to the DEM from a failing pump motor.