ECU Fault code 26
Discussion
My 89 Turbo SE is giving Fault code 26. (I used Freescan to get this). Code 26 says "Quad driver circuit, secondary injectors". I have to confess at not knowing exactly what the QDC is; something to do primary injectors?? The "Check Engine" lights around 21 seconds after the engine is started, every time, & stays on.
The vehicle runs as I would expect, & everything appears to work, but I cannot find what is causing this. I read an entry by Danny Tattersall on this site this morning which suggested it might be something to do with the charcoal filter cannister solenoid. I have checked just checked this - 12V ok across the pair of wires to it with IGN on, & the solenoid appears electrically ok (45 ohms), although having said that I cannot hear it clunk when I disconnect/connect it like I can with the other solenoids. Surely though, the ECU can only know that it's electrically operated as opposed physically operated?
Prior to doing this I checked the secondary injector cct & found nothing wrong, assuming that they are higher resistance than the primaries (17 against 2.5 ohms). I have also checked all other engine associated relays, fuses, vacuum & pressure pipes - all OK.
Any ideas please?
Mark
The vehicle runs as I would expect, & everything appears to work, but I cannot find what is causing this. I read an entry by Danny Tattersall on this site this morning which suggested it might be something to do with the charcoal filter cannister solenoid. I have checked just checked this - 12V ok across the pair of wires to it with IGN on, & the solenoid appears electrically ok (45 ohms), although having said that I cannot hear it clunk when I disconnect/connect it like I can with the other solenoids. Surely though, the ECU can only know that it's electrically operated as opposed physically operated?
Prior to doing this I checked the secondary injector cct & found nothing wrong, assuming that they are higher resistance than the primaries (17 against 2.5 ohms). I have also checked all other engine associated relays, fuses, vacuum & pressure pipes - all OK.
Any ideas please?
Mark
Mark,
I had a code 26 on my '89 non-SE for seven years. Had it checked at the Dealer too. Their are about 8 items it could be, you will only be able to tell from other things that might show up. See other posts in this forum to tell you what they could be. The only thing I finally did was change the ECM out but only after the timing circuits, the fuel pump relay circuit, and was told by Marcus that my chip had gone south, evidenced by the radiator fans coming on as soon as you turn the ignition on, did the code 26 stop.
The car still would make 135 mph, gave good, 25 mpg, mileage, start on the first crank and did all the things it should. Even the dealers will say, "does it run fine?" Yes? No Problem.
So, good luck.
lotusman
'89 non-SE
I had a code 26 on my '89 non-SE for seven years. Had it checked at the Dealer too. Their are about 8 items it could be, you will only be able to tell from other things that might show up. See other posts in this forum to tell you what they could be. The only thing I finally did was change the ECM out but only after the timing circuits, the fuel pump relay circuit, and was told by Marcus that my chip had gone south, evidenced by the radiator fans coming on as soon as you turn the ignition on, did the code 26 stop.
The car still would make 135 mph, gave good, 25 mpg, mileage, start on the first crank and did all the things it should. Even the dealers will say, "does it run fine?" Yes? No Problem.
So, good luck.
lotusman
'89 non-SE
Thanks for the info Guys. Hope it's not my ECU - only had a new one 2 years ago due to false temperature readings causing inability to start.
Had a quick look at the filler neck tubes on the ECU side. The one to the cannister has some fine cracks for the 1st couple of inches but is otherwise OK, but the one that links to the other filler neck has several deep scores that look almost like knife cuts, with rather gaping holes. No wonder my engine bay smells of fuel! Lucky I gaven't blown myself up. Not checked the other side yet, but I guess it's probably the same.
I'll let you know the outcome.
Thanks again,
Mark
Had a quick look at the filler neck tubes on the ECU side. The one to the cannister has some fine cracks for the 1st couple of inches but is otherwise OK, but the one that links to the other filler neck has several deep scores that look almost like knife cuts, with rather gaping holes. No wonder my engine bay smells of fuel! Lucky I gaven't blown myself up. Not checked the other side yet, but I guess it's probably the same.
I'll let you know the outcome.
Thanks again,
Mark
I still have a Code 26 problem to this day. Judging by what you have said though, I think that you may have a problem with one of the solenoids in the rear compartment. If the engine is running and you disconnect one at a time and wait for 20 seconds then the light will come on. That is because it takes 20 seconds before the ECU acknowledges it as a hard fault as opposed to being an intermittent fault. Let me know how you get on. I have put 12V across all the solenoids and they work correctly. My fault is only apparent during low speed driving. If I was to stay on the motorway the fault does not occur. However, as soon as I slow down and get on to urban roads the Code 26 appears.
Good luck,
Danny '93 SE Highwing
Good luck,
Danny '93 SE Highwing
Leachyboy,
Further to my reply earlier, I changed my ECU to no avail. However, if you would like to try a replacement ECU in yours then you can borrow my spare one if you are prepared to come to Huntingdon (Cambridegeshire) with the car one evening. It is probably about a hundred miles or so from where you are.
Danny '93 SE Highwing.
Further to my reply earlier, I changed my ECU to no avail. However, if you would like to try a replacement ECU in yours then you can borrow my spare one if you are prepared to come to Huntingdon (Cambridegeshire) with the car one evening. It is probably about a hundred miles or so from where you are.
Danny '93 SE Highwing.
Code 26 is indeed a Quad Driver Module failure.
The "Quad Driver Module" is a driver transistor inside the ECM. Think of it as 4 seperate output amplifiers packaged into one small IC.
The microcontroller inside the ECM sends an output signal to this IC, and it amplifies the logic level input to control a 12 volt output. The chip has a fail safe built into it, so that if it turns an output on, and there is not the correct amout of current draw on that output, it send a signal back to the microcontroller. This lack of current draw is typically from an open circuit, like a bad injector or disconnected selenoid (or a blown fuse) Unfortunatly it has only one "fail" output, so you don't really know which circuit has failed, After the microcontroller has sampled the failure for a given time, it then sets the MIL ("Malfunction Indicator Light" or Check engine light to most) to a code 26.
The Quad drivers control:
Secondary injectors
Canster Purge selonoid
Throttle Jack/EBPV selenoids
to name a few...
The Quad Driver modules outputs are a low signal, they supply the ground to the circuit, for instance, the secondary injectors get their +12 power from a fuse, a constant supply when the engine is running. They get a switched ground signal from the quad driver.
Due to your comment that is seems to happen at low speeds, I would look to the canster purge selenoid.
The "Quad Driver Module" is a driver transistor inside the ECM. Think of it as 4 seperate output amplifiers packaged into one small IC.
The microcontroller inside the ECM sends an output signal to this IC, and it amplifies the logic level input to control a 12 volt output. The chip has a fail safe built into it, so that if it turns an output on, and there is not the correct amout of current draw on that output, it send a signal back to the microcontroller. This lack of current draw is typically from an open circuit, like a bad injector or disconnected selenoid (or a blown fuse) Unfortunatly it has only one "fail" output, so you don't really know which circuit has failed, After the microcontroller has sampled the failure for a given time, it then sets the MIL ("Malfunction Indicator Light" or Check engine light to most) to a code 26.
The Quad drivers control:
Secondary injectors
Canster Purge selonoid
Throttle Jack/EBPV selenoids
to name a few...
The Quad Driver modules outputs are a low signal, they supply the ground to the circuit, for instance, the secondary injectors get their +12 power from a fuse, a constant supply when the engine is running. They get a switched ground signal from the quad driver.
Due to your comment that is seems to happen at low speeds, I would look to the canster purge selenoid.
Leachyboy,
Sorry to butt in on your post but hopefully the responses may help us both to solve our Code 26 problem........
Squelch,
Thanks for that. I looked at the cannister purge solenoid because it was happening at low speed but it appears to work okay. The only way that I could really check it was to put 12V across it directly from the battery. The 'click' as it operated was not as strong as I found when I checked the other solenoids though. I then substituted the solenoid for a 12V bulb to complete the circuit. The Code 26 still appeared but it did not come on after 20 seconds - it came on under similar circumstance to those with the solenoid connected. My conclusion from this is that I do not have a problem with that particular solenoid. I tried this technique with the other soleniods and could not find any problem with them either. As a result I am running out of ideas. Have you any other thoughts?
Danny '93 SE Highwing
Sorry to butt in on your post but hopefully the responses may help us both to solve our Code 26 problem........
Squelch,
Thanks for that. I looked at the cannister purge solenoid because it was happening at low speed but it appears to work okay. The only way that I could really check it was to put 12V across it directly from the battery. The 'click' as it operated was not as strong as I found when I checked the other solenoids though. I then substituted the solenoid for a 12V bulb to complete the circuit. The Code 26 still appeared but it did not come on after 20 seconds - it came on under similar circumstance to those with the solenoid connected. My conclusion from this is that I do not have a problem with that particular solenoid. I tried this technique with the other soleniods and could not find any problem with them either. As a result I am running out of ideas. Have you any other thoughts?
Danny '93 SE Highwing
Squelch,
Thanks, but I bought the ECU supplement and so I know what the solenoids, relays etc are that are controlled by the quad drivers. There are A and B faults but freescan does not tell you which of these categories your particular problem lies in unlike the proper Lotus diagnostic tool. Anyway, I have looked at absolutely everything on the list and can not locate the problem. Even a Lotus specialist (PNM) were not really willing to look at it and talked me out of taking it to them over the phone!
Danny '93 SE Highwing.
Thanks, but I bought the ECU supplement and so I know what the solenoids, relays etc are that are controlled by the quad drivers. There are A and B faults but freescan does not tell you which of these categories your particular problem lies in unlike the proper Lotus diagnostic tool. Anyway, I have looked at absolutely everything on the list and can not locate the problem. Even a Lotus specialist (PNM) were not really willing to look at it and talked me out of taking it to them over the phone!
Danny '93 SE Highwing.
I'm so glad I found this WEB site, you are all very helpful, thanks.
The story so far...
In the absence of any pipe to hand, I taped up my split filler neck breather hose to see if it made any difference - alas not, but I will do a proper fix anyway. I then decided to look in the cannister solenoid area again, since on my 1st look I couldn't hear it "clunk" when I put the lead to it on & off. I rechecked the voltage in the wires - 12V with IGN on & the lead disconnected. Knowning a little about electrics though, I know testing for voltage on an "open" circuit can be misleading, since if either of the wires is resistive you will still see 12V. I then checked the individual wires for resistance - one to the solenoid fuse & the other to the ECU - both were OK. I then reconnected the lead to the cannister to measure the resistance through the whole cct. - 350 ohms?? wasn't like that last time I measured it! I fiddled with the connector & the reading was all over the place. Although, after being a bit more specific about what I was moving I think it is actually the solenoid itself causing the erractic resistance, rather than the connector. After a bit of pulling, pushing & squeezing it seemed to settle at around 40 ohms & then stopped changing. Turned IGN on - still didn't operate! I then tried operating one of the other solenoids with the cannister lead - nothing. Measuring the current flow on the EBPV with it's own lead I get around 300mA, but with the cannister lead on the EBPV solenoid I only get 0.3mA, er, not enough to energise it! My only deduction from all this it that the cannister solenoid is duff & probably went short circuit, which in turn has wrecked the transistor or whatever in the ECU that operates it. Oh gloom!
Danny,
thanks so much for your offer - I may take you up on it. I do have another ECU but that has an intermittent water temp fault that stops the engine starting (thinks the engine is hot when it's stone cold & so doesn't apply cold start rules). Think I need to sort out the cannister solenoid 1st though. If it comes to bits I'll have a jolly good try at fixing it!
I'll have a think about your problem too, being as I have learned an awfull lot in the last few weeks. If you go motorway, urban, motorway, does it go out again?
Squelch,
Thanks for the info. You seem to have excellent knowledge of the ECU circuitry, don't suppose you have a diagram of it? Or do you know which transistor/chip is the solenoid driver. Cos if that is broke, I'll try to fix that too!
Mark
The story so far...
In the absence of any pipe to hand, I taped up my split filler neck breather hose to see if it made any difference - alas not, but I will do a proper fix anyway. I then decided to look in the cannister solenoid area again, since on my 1st look I couldn't hear it "clunk" when I put the lead to it on & off. I rechecked the voltage in the wires - 12V with IGN on & the lead disconnected. Knowning a little about electrics though, I know testing for voltage on an "open" circuit can be misleading, since if either of the wires is resistive you will still see 12V. I then checked the individual wires for resistance - one to the solenoid fuse & the other to the ECU - both were OK. I then reconnected the lead to the cannister to measure the resistance through the whole cct. - 350 ohms?? wasn't like that last time I measured it! I fiddled with the connector & the reading was all over the place. Although, after being a bit more specific about what I was moving I think it is actually the solenoid itself causing the erractic resistance, rather than the connector. After a bit of pulling, pushing & squeezing it seemed to settle at around 40 ohms & then stopped changing. Turned IGN on - still didn't operate! I then tried operating one of the other solenoids with the cannister lead - nothing. Measuring the current flow on the EBPV with it's own lead I get around 300mA, but with the cannister lead on the EBPV solenoid I only get 0.3mA, er, not enough to energise it! My only deduction from all this it that the cannister solenoid is duff & probably went short circuit, which in turn has wrecked the transistor or whatever in the ECU that operates it. Oh gloom!
Danny,
thanks so much for your offer - I may take you up on it. I do have another ECU but that has an intermittent water temp fault that stops the engine starting (thinks the engine is hot when it's stone cold & so doesn't apply cold start rules). Think I need to sort out the cannister solenoid 1st though. If it comes to bits I'll have a jolly good try at fixing it!
I'll have a think about your problem too, being as I have learned an awfull lot in the last few weeks. If you go motorway, urban, motorway, does it go out again?
Squelch,
Thanks for the info. You seem to have excellent knowledge of the ECU circuitry, don't suppose you have a diagram of it? Or do you know which transistor/chip is the solenoid driver. Cos if that is broke, I'll try to fix that too!
Mark
Leachyboy,
My check engine light does not go out when I go from urban to motorway. If the fault occurs for 20 seconds or more it becomes a 'hard fault' and not an intermittent fault. The only way to get the light to go off is to switch the ignition off and then back on again. The fault will be stored in the ECU until you reset it with freescan but at least the light stays off for a while and you get full boost again.
I am not very competent on electrics and so most of what you said in your last post went over my head!
Don' t hesitate to let me know when you have fixed your solenoid if you need the ECU.
Danny.
My check engine light does not go out when I go from urban to motorway. If the fault occurs for 20 seconds or more it becomes a 'hard fault' and not an intermittent fault. The only way to get the light to go off is to switch the ignition off and then back on again. The fault will be stored in the ECU until you reset it with freescan but at least the light stays off for a while and you get full boost again.
I am not very competent on electrics and so most of what you said in your last post went over my head!
Don' t hesitate to let me know when you have fixed your solenoid if you need the ECU.
Danny.
Sorry Danny, didn't mean to baffle you with science. Basic electrics/electronics are second nature to me - been mending broken telephone exchanges for rather a long time! Cars are a different thing though! But I'm learning!
Think we have to solve your code 26 by eliminating what it couldn't be.
I'll be in touch.
Mark
Think we have to solve your code 26 by eliminating what it couldn't be.
I'll be in touch.
Mark
Glad I could help, sorry for the delayed response..
I do have a diagram of the ECU and some photos of it you can clearly see the quad drivers, I can pull the part numbers if you would like.
However, the current price of an ECM is so low (under $200) is it really worth trying to fix it yourself ?
I do have a diagram of the ECU and some photos of it you can clearly see the quad drivers, I can pull the part numbers if you would like.
However, the current price of an ECM is so low (under $200) is it really worth trying to fix it yourself ?
I had the same problem a while back in my 90 SE. I solved it by replacing both the secondary injector solenoid (or resisitor, don't remember what it was called) and the wastegate solenoid. Both are located in the back compartment. Not sure which one did the trick as I replaced them at the same time.
Hi Squelch,
Been busy doing other things so haven't touched the car for a while. I'd appreciate the diagram if possible (mark.leach@btopenworld.com). I'm guessing the quad drivers are the "Linear ICs" that are mounted vertically against the heat-sink, and not those big square surface mounted ones - they are so difficult to solder! If I can buy the chip & change it, I will. Not sure how much a "plain" GM ECU costs in the UK but last time I had an ECU fault I let the dealer fix it. They charged me $950 for a "Genuine" Lotus one!
Been busy doing other things so haven't touched the car for a while. I'd appreciate the diagram if possible (mark.leach@btopenworld.com). I'm guessing the quad drivers are the "Linear ICs" that are mounted vertically against the heat-sink, and not those big square surface mounted ones - they are so difficult to solder! If I can buy the chip & change it, I will. Not sure how much a "plain" GM ECU costs in the UK but last time I had an ECU fault I let the dealer fix it. They charged me $950 for a "Genuine" Lotus one!
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