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For 1990-2009 cars only

ECC SYSTEM CONTROL TOO COLD HEADER MODE (NEW PARTS)

SUBJECT: ECC SYSTEM CONTROLS TOO COLD (HEATER MOD

MODELS AFFECTED: 1989-1991 ELDORADOS AND SEVILLES

This bulletin supersedes Service bulletin T-90-17 which should be discarded. This bulletin is being revised to add the 1990 and 1991 model years and update part numbers.

Some 1989-1991 Eldorados and Sevilles may experience a condition of insufficient. interior temperature after vehicle is driven for a sustained period.

To repair this condition use the following procedure:

1. Perform ECC system check outlined in Section 1C of the Service Information Manual.

2. If system check indicates no problem, check BCM PROM I.D. (diagnostic parameter BD99) with the chart below. If vehicle PROM I.D. corresponds with original PROM I.D. listed, replace with new PROM I.D. as indicated in the chart.

PROM CHART

| ORIGINAL PROM I.D. | NEW PROM I.D. ------------------------------------------------------------------------- Broadcast PROM | Broadcast Code I.D. | Code I.D. P/N -------- ----- | ------- ----- -------- 1989 ANDP 3776 | AUKN 1046 16151037 APYK 3426 | ASAP 8766 | | 1990 ANXX 9236 | AUKP 1056 16151314 | 1991 AUUY 5996 | AYDR 4606 16164604 AWNF 6416 | |

Parts are currently available from GMSPO.

For warranty purposes use Labor Operation N4801 at .5 hour.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.