![]() As outlined previously by AmericaSpace, the presidential inquiry into the loss of Challenger uncovered a string of cultural and managerial shortcomings, in addition to the root technical cause of the disaster, a cold-induced failure of O-ring seals within one of the twin Solid Rocket Boosters (SRBs). Yet fundamentally, in the words of STS-26 Commander Rick Hauck, the main purpose of the mission “was simply to fly again”, after almost two years of introspection and public and political anger and uncertainty over the avoidable accident that Mission 51L had been. Last edited by Lukeyson on Wed 12:12 am, edited 2 times in total.STS-26, the 26th mission of the shuttle program and seventh for frequent-flying Discovery, would deploy a large NASA Tracking and Data Relay Satellite (TDRS) into orbit to permit communications between future astronaut crews and ground stations, as well as relaying data from major scientific spacecraft, including the Hubble Space Telescope (HST). I'll have to get that BF XR6T back again and rescan it because I have room to doubt myself that I recorded that correctly. However, I've got a lot of data, and another BF I have scanned has a different BEM part number. So the next question is whether the TILA and RKR are the same with just a change of the lock barrell. That means to me that Smartshield hasn't changed between the BA and BF since the major participants in Smartshield are the PCM and the BEM. This does imply a loom change though if you want to retain the Alternator display on your IC.īut as for your Smartshield concerns - I have a scan here which shows a BF XR6T with a BA BEM part number. So whether this change in alternator sensing operation needs a different IC or not I don't know, since the IC uses the same input pin to drive the light on BA or BF. So a BA PCM might not know that the alternator has failed! That's bizarre. On the BA, the Alternator sensor is connected directly to the IC. The BF instead uses those pins for the PCM to sense the output of the Alternator, and a 3rd pin is connected to the IC to show whether the Alternator is OK. But the BF only has one, and the 2nd PPS power is instead driven from the power that feeds the PRNDL TRS-A2 Tiptronic sender - which would be a CAN module in the BF. Well, the BA PCM drives 2 x VREF power sources into the Pedal Position Sensor box (stay with me here.). The airbags still haven't been stopped, and I'm still in favour of the BF RCM going in, but it looked for a moment like there might be a possible show stopper for the BF option. Thankfully a review of the BF Manual shows the same TAS frequencies, and the same pin on the RCM. 'DTC P1534 - TAS signal outside of allowable frequency range or not present The TAS is tested continuously during vehicle operation. 'If the TAS signal is not within the normal operating frequency range or not present at all, the PCM sets a DTC in memory for retrieval during self test mode. ![]() ![]() The PCM detects the change in frequency of the TAS signal and places on the CAN bus in message 427, bit 6, where circumstances allow it, a message to the BEM that the RCM has registered an impact and that the doors should be unlocked. In the event of an impact that is registered by the RCM, the RCM changes the frequency of the TAS signal to 5Hz for 5 cycles only. During a non impact phase, the frequency read by the PCM is 0.8Hz. The PCM recieves a continuous 12 Volt square wave signal on pin B6 while the ignition is on, from the Restraint Control Module, RCM. 'The TAS signal consists of two distinct frequencies, one for normal conditions and a higher frequency for impact event notification. The workshop manual describes the operation of the BA TAS line as thus: Of interest, though, is a single hardwired line between the PCM and the Restraint module called the TAS line - Travel Assistance Signal. There are other differences as well, but that would be another topic. Enough of a difference to make it look like it wouldn't be an easy task to swap a BF PCM into a BA without also changing a whole heap of looms - especially for 4A cars, where the pins for controlling the solenoids have all completely moved from EEC-B/C-301 to EEC-C/C-302. Of itself, that's a bit of an eye opener, seeing how many differences there really are. On a whim I bought a BF PCM, and started mapping out pins between them. But it turns out the BA and BF TAS operation is the same.
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