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 UE1

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

Models: | All 00-08 Gen 4, 5, 6 and 7 OnStar® equipped vehicles

This PI was superseded to update model years and Recommendation/Instructions. Please discard PIC3341C.

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

### Condition/Concern:

Some 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 VCIM.

### Recommendation/Instructions:

When following eSI diagnostics for DTC B2470 , the cellular coax cable should be disconnect at the VCIM with the coax cable still connected to the antenna base. There is a possibility of corrosion or poor connection at the antenna base or coupler box. Often the concern is resolved by simply cycling the connection at the module or antenna base.

A quick check to determine if the antenna/coax assembly or the VCIM is the cause of the B2470 is to disconnect the cell antenna coax from the VCIM then connect a jumper wire from the center pin of the cellular antenna connector @ the VCIM and ground it to the shield (threaded portion) of the connector. Turn on the vehicle ignition and check for codes in the VCIM. If the B2470 goes to history, the VCIM is working as designed. Reconnect the cell antenna coax to the VCIM and again check for codes. If the B2470 is not present after reconnecting the cell antenna coax to the VCIM, recheck terminal tension at the VCIM to coax connection.

If the B2470 remains after the above test is made then test the coax and antenna as an assembly. OnStar® uses several different cellular antennas depending on vehicle application.

Typical readings are as follows:

Glass Mount antenna: 1 ohm or less.

Roof mount combination antenna (cell & GPS): 995 ohms.

Tri-band/quad band antenna (cell, GPS and satellite radio-if equipped): 4.7 kOhms.

If the measurements are out of specification, then the cellular coax should be disconnected from both the VCIM and the antenna base. Measure the resistance of the coax cable 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 visually 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.

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.