For 1990-2009 cars

# Intermittent Red LED DTC B2470 And Possible Unable To Contact OnStar Center - keywords analog blue button connect digital DTC information led no opc operation performance PIC3341 PIC3341A PIC3341B UE1

Subject: | Intermittent red LED, DTC B2470 and possible unable to contact OnStar center

Models: | All 2002-2007 Gen 4, 5, 6 and 7 OnStar equipped vehicles

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

### Condition/Concern:

Some OnStar customers may report an intermittent red LED and they are unable to use their OnStar system. The vehicle may have a current or history DTC B2470 present in the OnStar module. Possible corrosion or poor connection at the antenna base or coupler box.

### Recommendation/Instructions:

Prior to performing step two of SI Document ID # 745130 for the B2470 DTC, the cellular coax cable (White connector) should be disconnect at the VCU/VCIM with the coax cable still connected to the antenna base.

Measure center pin to shield to identify possible high resistance in the cable or base. (Glass mount should read 1 Ohm or less, roof mount 995 Ohms or less and tri-band/quad-band antenna (such as used on the SRX) 4.7 k-Ohms or less.)

If the measurements are out of specification then the cellular coax should be disconnected at the antenna base and the coax cable measured from center pin to center pin (should read 1 Ohm or less) and center pin to shield (should read OL)

If the cellular coax measurements are with in specification then the base or coupler box should be inspected for damage, corrosion and replaced if necessary.

The DTC should be cleared with the Tech 2 and the system tested to ensure the repair is complete.

Note: Glass mount antenna couplers should NOT be installed over any after market window tint.

A quick check to determine if the VCIM is the cause of the B2470 is to installed a jumper wire into the center pin of the cellular antenna connector @ the VCIM and ground it to the case. The unit will have to be installed and powered up in the vehicle, if the B2470 goes to history, the VCIM is working as designed and the antenna and coax cable should be serviced or replaced as needed.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.