| Re: 93 vett ABS/ASR code DTC72 |
Subject: Re: 93 vett ABS/ASR code DTC72 by Matatk on 2015/10/1 0:45:55 Quote:
Back to the beginning. From FSM 5E2-14: The EBTCM can display the DTCs through the use of the Central Control Module (CCM) on-board diagnostic capabilities, the Tech 1 Diagnostic Computer, or the T-100 (CAMS) unit. In almost all instances in this section, diagnosis, information display, and system/component actuation will be described using the Tech 1. Refer to SECTION 8D for details on using the CCM diagnostics for the ABS/ASR system. Based on that, there were two "off-board" systems for testing the EBTCM. The Tech 1, and the T-100. The T-100 was apparently a rare, full sized, roll around, computer based diagnostic machine used in GM dealers (based on what limited info I can find on the web). So when the troubleshooting guide says "off-board" device, this is why. Since the T-100 is obsolete and apparently extinct, you'll need a Tech 1. As far as the code that you already retrieved, DTC72: That is a serial data link malfunction, meaning there were errors in message transmission. Using the Test Description section 5E2-108, Test 1 indicates that if you do not have an off-board device, you can use the CCM to attempt to communicate with the EBTCM. (see section 8D - display ABS/ASR DTCs). So your first step in the troubleshooting tree is attempt to communicate with the EBTCM using the CCM. Since you already have the code, I will "assume" you got the code via the cluster? If that is the case, and you can communicate with the EBTCM, then you have no trouble there and you have to use the diagnostic aids under DTC 72. The Diagnostic Aids state: The problem may be intermittent. Try performing the tests shown while wiggling wiring and connectors; this can often cause the malfunction to appear. CCM DTC 41 will likely be set along with this DTC if the problem is a short to ground or B+ on the serial data circuit. If ABS/ASR DTC72 is set and CCM DTC 41 is not, the malfunction is likely to be an open between the EBTCM and the CCM. So, that being said.... 1) Do you have any other trouble codes (ie, CCM DTC 41)? 2) The other diagnostic tool needed is a J39700 breakout box, which allows you to test the voltage/resistance in the wires. This box looks pretty pricey for the average person. 3) If you don't have a CCM DTC 41, then you most likely have an open wire between the EBTCM and the CCM, and you'll need to track that down. 4) I would reset the code and see how quickly it comes back, or if you can make it appear by wiggling the connectors or individual wires. Hope that helps. |
