Electronic Cruise Problems...
06-01-2009, 03:31 PM
#1
Electronic Cruise Problems... Not sure if this is the right forum...but I'll give it a try here...
I just rewired my 56 Chevy that has an LS1 and Electronic Cruise Control (I did not change out the wiring harness...great harness from Speartech), and while doing this, I called Classic Instruments to ask if they had any improvments related to their BelEra guages hooked up to a PCM and LS1 combination. (It would jump occasionally to 120, and when initially coming to a stop, the speedo would run at 10mph for 2-3 seconds after stopping.)
They said to not hook to the speedo wire from the PCM but directly to the VSS High wire out of the transmission, before the PCM.
Well, the speedo works better now, but the electronic cruise control was flaky. Actually, for about 2 weeks, the cruise worked perfectly.
But then a couple weeks ago, at 55mph, or less, it worked flawless. But try to run any faster than that, and the car would surge and run very erratically, especially at 60 or higher. Once it even kicked down into passing gear.
I thought maybe I need to shield the wire running between the speedo and the VSS High wire at the transmission. (Although I'm not sure why it would work great for a copule weeks first) So I ran a new wire, this time not bundled in the wire loom behind the engine with the other wires (but still going that route) and I wrapped a second wire (that is, I ended up with 2 wires twisted together for the entire path), and the second wire I grounded up under the dash, and at the frame near the transmission. ( I was told this would help shield the wire from interferance.)
So, I took it for a drive, It worked 90% better, but still not perfect. But it only did so for about 1 mile. I got up to about 70 mph, and using the cruilse. Traffick started slowing a little, and I pressed the coast button 3-4 times to slow down, and it quit altogether. No cruise at all now.
I'm beginning to think the TAC module has gone bad. Leaves me with a couple questions:
I should mention that the PCM is not putting out any codes.
Thanks
Roger
I just rewired my 56 Chevy that has an LS1 and Electronic Cruise Control (I did not change out the wiring harness...great harness from Speartech), and while doing this, I called Classic Instruments to ask if they had any improvments related to their BelEra guages hooked up to a PCM and LS1 combination. (It would jump occasionally to 120, and when initially coming to a stop, the speedo would run at 10mph for 2-3 seconds after stopping.)
They said to not hook to the speedo wire from the PCM but directly to the VSS High wire out of the transmission, before the PCM.
Well, the speedo works better now, but the electronic cruise control was flaky. Actually, for about 2 weeks, the cruise worked perfectly.
But then a couple weeks ago, at 55mph, or less, it worked flawless. But try to run any faster than that, and the car would surge and run very erratically, especially at 60 or higher. Once it even kicked down into passing gear.
I thought maybe I need to shield the wire running between the speedo and the VSS High wire at the transmission. (Although I'm not sure why it would work great for a copule weeks first) So I ran a new wire, this time not bundled in the wire loom behind the engine with the other wires (but still going that route) and I wrapped a second wire (that is, I ended up with 2 wires twisted together for the entire path), and the second wire I grounded up under the dash, and at the frame near the transmission. ( I was told this would help shield the wire from interferance.)
So, I took it for a drive, It worked 90% better, but still not perfect. But it only did so for about 1 mile. I got up to about 70 mph, and using the cruilse. Traffick started slowing a little, and I pressed the coast button 3-4 times to slow down, and it quit altogether. No cruise at all now.
I'm beginning to think the TAC module has gone bad. Leaves me with a couple questions:
- Will the car run normally (except for the cruise control) if the TAC module is bad?
- Do any of you think that the way I wired this would be the cause of my problem? Or just coincidental?
- Any thoughts or suggestions?
I should mention that the PCM is not putting out any codes.
Thanks
Roger
06-01-2009, 09:26 PM
#2
I'm a bit surprised I haven't at least gotten an answer about if the throttle would work or not if the TAC module is bad...but I do have an update.
I am getting the cruise to work intermittently. I have tested the function of the relays in the system, and they appear to be functional.
I am quite suspicious of the connector I used from the turn signal stalk. In the next few days I plan to replace that and make sure the connections are good.
I'm fairly confident at this point it is not the TAC module.
I'll post back what I find for anyone that may be interested.
I am getting the cruise to work intermittently. I have tested the function of the relays in the system, and they appear to be functional.
I am quite suspicious of the connector I used from the turn signal stalk. In the next few days I plan to replace that and make sure the connections are good.
I'm fairly confident at this point it is not the TAC module.
I'll post back what I find for anyone that may be interested.
06-12-2009, 03:12 PM
#3
Well, I"m having no luck. Replacing that connector did seem to fix the surging problem, but then it worked only intermittently.
Now it seems to have stopped altogether.
Pulling the speedo wire from the VSS High wire makes no difference.
I"m going to take it to a shop and have them put it on a scope and see if they can tell anything. I"m about to decide that the TAC module is bad. I guess my concern is whether hooking to that VSS wire caused it, or if it is coincidental.
Given that the speedo was a bit flaky when it was hooked up to the wire from teh PCM, maybe that was a symptom that the TAC module was not all it should be, and it has not just gone out.
I'd hate to put a $250 TAC module on just to blow it out again.
If anyone has any thoughts that know about this stuff it would be apprecaited.
Now it seems to have stopped altogether.
Pulling the speedo wire from the VSS High wire makes no difference.
I"m going to take it to a shop and have them put it on a scope and see if they can tell anything. I"m about to decide that the TAC module is bad. I guess my concern is whether hooking to that VSS wire caused it, or if it is coincidental.
Given that the speedo was a bit flaky when it was hooked up to the wire from teh PCM, maybe that was a symptom that the TAC module was not all it should be, and it has not just gone out.
I'd hate to put a $250 TAC module on just to blow it out again.
If anyone has any thoughts that know about this stuff it would be apprecaited.
06-13-2009, 10:43 PM
#5
thing to do is hook up a scan tool and see if the MPH reading it is getting is changing. My drive by wire setup on a 5.3 surges with cruise on, only because the trigger wheel i made is a little off center. (using turbo 400, with trigger wheel mounted on rear end yoke). The MPH jumps around 2-3 mph most of the time. I needed vss more to fix idle issue then have cruise, eventually I'll fix the trigger wheel so cruise works better.
you might try unhooking the speedometer all together, see if the surge problem goes away.
you might try unhooking the speedometer all together, see if the surge problem goes away.
06-15-2009, 09:27 AM
#6
thanks Busta
Sorry, my comment in my last post was not clear enough. I did disconnect the speedo altogether, and it made no difference.
I should restate: I'm not having problems with it pulsating now. It just flat out does not work.
I hope to get it on a scope at a shop this week and see what they can tell.
I've not had anyone yet tell me that in fact the cruise can be non-functional, and the engine otherwise run normally. I had presumed, (it seems maybe incorrectly) that if the TAC module went out the engine wouldn't function either. But given that I have tested and the cruise stalk on the column seems to be sending the signals correctly, and nothign...I'm thinking at this point that the TAC module is bad.
I"m also beginning to wonder if maybe the TAC module was never really perfectly good, and that was what was causing my speedo to be erratic. And not it's gone out altogether. What I don't want to do us get another expensive TAC module and put it in to ruin it if in fact hooking the SPEEDO wire direct to the VSS is what is causing it to fail. According to Classic Instruments, they have other people running this way, so hopefully that is not the problem.
Sorry, my comment in my last post was not clear enough. I did disconnect the speedo altogether, and it made no difference.
I should restate: I'm not having problems with it pulsating now. It just flat out does not work.
I hope to get it on a scope at a shop this week and see what they can tell.
I've not had anyone yet tell me that in fact the cruise can be non-functional, and the engine otherwise run normally. I had presumed, (it seems maybe incorrectly) that if the TAC module went out the engine wouldn't function either. But given that I have tested and the cruise stalk on the column seems to be sending the signals correctly, and nothign...I'm thinking at this point that the TAC module is bad.
I"m also beginning to wonder if maybe the TAC module was never really perfectly good, and that was what was causing my speedo to be erratic. And not it's gone out altogether. What I don't want to do us get another expensive TAC module and put it in to ruin it if in fact hooking the SPEEDO wire direct to the VSS is what is causing it to fail. According to Classic Instruments, they have other people running this way, so hopefully that is not the problem.
06-15-2009, 09:33 AM
#7
If the latter, I suspect that Ididit is using a Rostra stalk in their column and that would require the use of 2 relays to get it to work with the electronic setup. I can share a wiring diagram for that if you need.
If anyone is wondering why 2 relays would be needed: The electronic cruise needs a normally open switch, and all the aftermarket switches are normally closed.
Here is a link to a thread from when I was working that issue with a diagram.http://www.chevytalk.org/fusionbb/sh...?post/1249603/
