Guest crtnrds Posted April 20, 2015 Share Posted April 20, 2015 Got my '90 convert back having had a new heater core installed and the speedometer is now not working. My manuals' index lists speedometer diagnosis in 7A-14 but there is no mention of the speedometer on that page. Any ideas? Link to comment Share on other sites More sharing options...
KDirk Posted April 20, 2015 Share Posted April 20, 2015 Is it on but reading 0 or is the display actually off (blacked out)? Two different problems and troubleshooting procedures depending on which symptom is present.KDirk Link to comment Share on other sites More sharing options...
Guest crtnrds Posted April 20, 2015 Share Posted April 20, 2015 It is on but reading 0. Link to comment Share on other sites More sharing options...
KDirk Posted April 20, 2015 Share Posted April 20, 2015 Ok so so sounds like the vehicle speed data isn't getting to the BCM which then sends it along to the IPC. Could be as simple as a wiring issue caused by work done in the dash (heater core). I would follow the troubleshooting tree in the FSM since you have it on hand. I take it all the other gauges are working so the BCM is forming a data stream to send to the cluster it just doesn't include the VSS data. Could be a circuit not making at either the ECM or BCM or the sensor itself which is located on the transmission. You can enter diagnostics and check ECM data to see if the vehicle speed signal is making it that far. If so, the issue is after the ECM. Can also check BCM data to verify VSS data is absent there. If so, check the wiring between the two modules. KDirk Link to comment Share on other sites More sharing options...
Guest crtnrds Posted April 20, 2015 Share Posted April 20, 2015 (edited) You are correct in your assumption that the other gauges are working properly. This is a '90 so it does not have the diagnostic CRT to check the ECM and BCM data. I can't crawl under the dash any more which is why I took it to a shop to replace the heater core in the first place. Guess I'll have to take it back to him (a friend). He must have not reconnected something properly when he replaced the heater core. Edited April 20, 2015 by crtnrds (see edit history) Link to comment Share on other sites More sharing options...
Guest crtnrds Posted April 21, 2015 Share Posted April 21, 2015 I looked at the FSM but electronics is not my forte. I can't tell what wire is what...seems like a brown wire has something to do with the speedometer??? HELP. KDirk, anybody. Link to comment Share on other sites More sharing options...
Ronnie Posted April 21, 2015 Share Posted April 21, 2015 Start with the basics. Does your cruise control work? If it does that rules out the speed sensor and proves the BCM is getting a signal from the sensor. Link to comment Share on other sites More sharing options...
Guest crtnrds Posted April 21, 2015 Share Posted April 21, 2015 The cruise control does not work, although I couldn't swear that it did before, but there in no indicator that says "cruise control problem". Sorry I am not more help but when you have 3 Reattas and are almost 70 years old. I can't remember what doesn't work on which car. Link to comment Share on other sites More sharing options...
Ronnie Posted April 21, 2015 Share Posted April 21, 2015 I went back and read your previous posts. Since you can't get under the dash I would take it back to your friend. Even if we were able to pinpoint the problem it's likely you will have to go into the dash to fix it. Link to comment Share on other sites More sharing options...
Guest crtnrds Posted April 21, 2015 Share Posted April 21, 2015 Thanks, guys for your help. I'm bringing it back tomorrow. Link to comment Share on other sites More sharing options...
Barney Eaton Posted April 22, 2015 Share Posted April 22, 2015 First place to check is the sending unit. Drivers side on top of the transmission. Link to comment Share on other sites More sharing options...
Machiner 55 Posted April 22, 2015 Share Posted April 22, 2015 (edited) Click on pic to select pic. Click on pic to get Magnifier. Click again to enlarge pic.John F. Edited April 22, 2015 by Machiner 55 (see edit history) Link to comment Share on other sites More sharing options...
harry yarnell Posted April 22, 2015 Share Posted April 22, 2015 Barney, are you talking about the VSS? It's on the passengers side near the CV joint. Link to comment Share on other sites More sharing options...
wws944 Posted April 22, 2015 Share Posted April 22, 2015 You are correct in your assumption that the other gauges are working properly. This is a '90 so it does not have the diagnostic CRT to check the ECM and BCM data...The diagnostic capability is there on the '90, but it uses the instrument cluster instead. To enter it, turn the key on without starting the engine. Then simultaneously press and hold the 'OFF' and '^' on the HVAC controls. After a few seconds, the IPC will black out, then reappear with all segments lit, then display error codes in the area where the odometer readout normally resides. You can then follow the prompts as mentioned in the service manual to look at various data values.From Ronnies site: http://reattaowner.com/roj/component/content/article/57-diagnostic-information/diagnostic-instructions/82-how-to-access-ecm-bcm-a-crt-codes#2-how-to-access-the-codes-for-90-91-models Link to comment Share on other sites More sharing options...
Guest crtnrds Posted May 4, 2015 Share Posted May 4, 2015 Thanks guys. It was a loose connector on the BCM. Link to comment Share on other sites More sharing options...
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