Erratic speedo
03-08-2005, 02:58 PM
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Erratic speedo
Just on the off-chance that someone has experienced the same thing...(1984 S2)
Speedo works at first, after a few minutes stops working. Replaced sender, no change, still works initially but stops. On a long run speedo came back for a few minutes then stopped again.
Any suggestions?
Speedo works at first, after a few minutes stops working. Replaced sender, no change, still works initially but stops. On a long run speedo came back for a few minutes then stopped again.
Any suggestions?
03-08-2005, 03:09 PM
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Racer
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Hvae you checked and cleaned the connector in the R hand corner of the spare wheel well - behind the black plastic cover? This is a common site for trouble but normally causes opposite symptoms - ie no speedo at first and then kicks in as speed picks up. Failing that sounds like speedo unit itself might be faulty.
Cheers
Mark
Cheers
Mark
03-08-2005, 04:15 PM
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Burning Brakes
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Actually, more common problem than you'd think. The 4-pin connector in the corner of the spare tire well is usually the culprit i.e. loose connection, dirty, not making good contact. My 84 has a loose connection in the pod... couple gentle whacks usually gets it back online. You can also check terminals T1 and T2 on the fuse panel (sending unit in) and H1/H2 (fuse panel to speedo) to make sure they're clean and tight. Wiring diagrams on pgs 97-17,97-19 show the pertinent connections. Failing to resolve it in those places usually means something amiss inside the pod. hth
03-09-2005, 10:08 AM
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I have a similar problem...intermitent speedo reading particularly noticable when the car is first used for the summer season. Most times the speedo will work first thing in the morning...quit breifly but start working again...then after a warm restart will not work at all for a while. Later in the day it will work normally and not miss a beat. My speedo has been serviced and verified to be working correctly, so I know the problem is not in the guage itself, FWIIW.
Here's a question: Do the speedo and the odometer quit working together or only the speedo? I have not been able to confirm, but I think there are seperate pickups for these, even though they are mounted on the same sender unit. In my case, my speedo will operate erratically, but the odo will not miss a beat.
Several things to check here:
1. The speedo/odo pickup in the transmission/differental (replaced as per your post);
2. The interconnect wiring harness in the spare tire well as others have mentioned (check for corrosion and good terminal contact). on my '85 there are 4 brown/red stripe wires that feed from the sender...there are only two contacts on the sender, so I have no idea why there are two seperate circuits for the same unit. As long as one set works everthing should be OK);
3. The card-edge connectors on the instrument cluster (pull the pod and clean the male connector with an eraser...clean the female connector with stiff cardboard. Lots of posts on this in the archive too);
4. The speedo unit itself (if you have not had reason to replace the odometer gear, now may be a good time to do this and verify that your speedo is A-OK);
5. And finally verify that the power supply to the cluster is in working order.
This last one is interesting, as there have been several posts about erratic cluster operation that seem to be related to power issues in the central electrical panel. The cluster is fed power from several sources, so the chance of one being intermittent and effecting a guage or two is quite possible (if unlikely). If you have not already done so, take the time to verify that all the fuses in the panel are correct amperage, make good contact and have clean terminals. There are plenty of threads in the archives on this topic.
You can actually "ohm-out" the sending unit at the connecctor in the spare tire area. This is what I did to verify that the sender was working. The sender just is an on/of pulse and mine to put this out just fine. You can intercept this signal at the cluster as well to help determine if the problem is in the wiring between front and rear.
My car seems to work through this problem as it is driven...by 1/2 way through the summer (or about 5000km) the speedo works fine all the time. The problem only seems to be after the winter layup and on warm restarts in the early seasonal period. I'm sure the problem is with the sender and some bad contact in the sending unit, but I have never witnessed this when I test it.
Since you have a new sender, the problem is likely in the wiring to the cluster, in the cluster or guage itself. I'd suggest cleaning the cluster connectors as the next step, if you have not already BTDT.
Regards,
SteveCo in St. John's
Here's a question: Do the speedo and the odometer quit working together or only the speedo? I have not been able to confirm, but I think there are seperate pickups for these, even though they are mounted on the same sender unit. In my case, my speedo will operate erratically, but the odo will not miss a beat.
Several things to check here:
1. The speedo/odo pickup in the transmission/differental (replaced as per your post);
2. The interconnect wiring harness in the spare tire well as others have mentioned (check for corrosion and good terminal contact). on my '85 there are 4 brown/red stripe wires that feed from the sender...there are only two contacts on the sender, so I have no idea why there are two seperate circuits for the same unit. As long as one set works everthing should be OK);
3. The card-edge connectors on the instrument cluster (pull the pod and clean the male connector with an eraser...clean the female connector with stiff cardboard. Lots of posts on this in the archive too);
4. The speedo unit itself (if you have not had reason to replace the odometer gear, now may be a good time to do this and verify that your speedo is A-OK);
5. And finally verify that the power supply to the cluster is in working order.
This last one is interesting, as there have been several posts about erratic cluster operation that seem to be related to power issues in the central electrical panel. The cluster is fed power from several sources, so the chance of one being intermittent and effecting a guage or two is quite possible (if unlikely). If you have not already done so, take the time to verify that all the fuses in the panel are correct amperage, make good contact and have clean terminals. There are plenty of threads in the archives on this topic.
You can actually "ohm-out" the sending unit at the connecctor in the spare tire area. This is what I did to verify that the sender was working. The sender just is an on/of pulse and mine to put this out just fine. You can intercept this signal at the cluster as well to help determine if the problem is in the wiring between front and rear.
My car seems to work through this problem as it is driven...by 1/2 way through the summer (or about 5000km) the speedo works fine all the time. The problem only seems to be after the winter layup and on warm restarts in the early seasonal period. I'm sure the problem is with the sender and some bad contact in the sending unit, but I have never witnessed this when I test it.
Since you have a new sender, the problem is likely in the wiring to the cluster, in the cluster or guage itself. I'd suggest cleaning the cluster connectors as the next step, if you have not already BTDT.
Regards,
SteveCo in St. John's